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al of our products 9 contribute to the social economic and institutional development of the communities in which we operate 10 implement effective and transparent engagement communication and independently verified reporting arrangements with our stakeholders regarding the role of the united nations in sustainable development and mining in the future we want resolution res 66 288 2012 the united nations contributed with the following considerations a that minerals and metals make a major contribution to the world economy and modern societies b that mining industries are important to all countries with mineral resources in particular developing countries in this sense mining offers the opportunity to catalyze broad based economic development reduce poverty and assist countries in meeting internationally agreed development goals when managed effectively and properly c that countries have the sovereign right to develop their mineral resources according to their national priorities and responsibility regarding the exploitation of resources described in the rio principles and d that mining activities should maximize social and economic benefits and effectively address negative environmental and social impacts the resolution claims to governments and businesses to foster the continued enhancement of responsibility and transparency and the efficiency of the significant existing mechanisms to avoid the illicit financial flows from mining activities moreover building on the millennium development goals mdgs the 17 sustainable development goals adopted by all united nations member states in 2015 after extensive global consultation process seek to rebalance and integrate the economic social and environmental pillars of sustainable development with a central focus on people planet prosperity and peace in order to align the activities of the mining sector with these global goals the united nations development programme undp has conducted a mapping exercise that identifies the key ways in which mining activities can have a positive or negative impact on the achievement of each of the sdgs the mapping exercise they have undertaken has identified those positive direct and indirect impacts of mining on sustainable development that should be enhanced and those negative impacts that must be mitigated mining activities do not always produce economic and social profits to the countries in which the operations are located since the mines in some cases are situated where there is bad governance including corruption before financial institutions invest in mining projects they require that companies produce evidence of a business program that adequately addresses sustainability issues in their projects they apply stringent rules on resource companies looking for funding in this sense many banks belong to the dow jones sustainability world index djswi the index was launched in 1999 as the first global sustain

ability benchmark and it tracks the performances of sustainable companies and provides money managers with tools to better manage their eco conscious portfolios moreover many financial institutions have also adopted the equator principles ep which ensure that projects are developed in a manner that is socially responsible and reflects sound environmental management practices however it needs to be recognized that the djswi and the equator principles are voluntary and nonbinding and many investors particularly in developing countries are not required to adhere to them the equator principles are a voluntary set of standards adopted by financial institutions for determining assessing and managing environmental and social risk in project finance activities they are considered the financial industry gold standard for sustainable project finance the equator principles financial institutions epfis have adopted the equator principles in order to ensure that the financed projects are developed in a manner that they are socially responsible and reflect sound environmental management practices thus the importance of climate change biodiversity and human rights is recognized and negative impacts on project affected ecosystems communities and climate should be avoided where possible if these impacts are unavoidable they should be minimized mitigated and or offset epfis review the equator principles from time to time based on implementation experience and in order to reflect ongoing learning and emerging good practice the ep are primarily intended to provide a minimum standard for due diligence to support responsible risk decision making according to this epfis commit to implementing the ep in their internal environmental and social policies procedures and standards for financing projects and will not provide project finance or project related corporate loans to projects where the client will not or is unable to comply with the ep where a project is proposed for financing the epfi will as part of its internal environmental and social review and due diligence categorize it based on the magnitude of its potential environmental and social risks and impacts principle 1 review and categorization such screening is based on the environmental and social categorization process of the international finance corporation ifc using categorization the epfi s environmental and social due diligence is commensurate with the nature the scale and stage of the project and the level of environmental and social risks and impacts the categories are as follows a category a projects with potential significant adverse environmental and social risks and or impacts that are diverse irreversible or unprecedented b category b projects with potential limited adverse environmental and social risks and or impacts that are few in number generally site specific largely reversible and readily addressed through mitigation measure

s and c category c projects with minimal or no adverse environmental and social risks and or impacts obviously the equator principles have greatly increased the attention and focus on social community standards and responsibility since 2010 they include robust standards for indigenous peoples labor standards and consultation with locally affected communities within the project finance mining market the most important lending institutions worldwide many of whom provide financing for mining activities have adopted the equator principles thus currently 83 epfis in 36 countries have officially adopted the ep covering over 70 percent of international project finance debt in emerging markets at a meeting with world bank personnel in washington in 1997 jim cooney at that moment director of international and public affairs with placer dome proposed that the industry had to act positively to recover its reputation and gain a social license to operate in a process that beginning at the level of individual mines and projects would over time create a new culture and public profile for the mining industry thomson and boutilier 2011 the concept of a social license to operate or simply social license soon entered in the vocabulary of the industry civil society and communities that host mines and mining projects thus the concept is in fact an outcome of sustainability the social license has been defined as existing where a mine or project has the ongoing approval within the local community and other stakeholders this includes not only local communities fig 7 8 indigenous people and governments but also the international community inherent in this concept is the belief that local communities should benefit from the mining project stevens 2010 therefore mining companies must communicate openly with all interested parties and stakeholders and they must have a solid sustainability record in order to have the social license social license to operate is intangible dynamic and nonpermanent because beliefs opinions and perceptions are subject to vary as new information is obtained hence the social license has to be gained and later retained it is commonly granted on a site specific basis thus a company can have a social license to operate for one mine but not for another one obviously the larger the effects the more difficult it becomes to get the social license to operate moreover the term to operate is in some cases confusing with the exclusively operational phase of a mine life cycle where mineralization is extracted for processing a better sense of the term to operate is to continue the project no matter where in the mine life cycle from starting exploration to closure and reclamation thomson and boutilier 2011 the exploration stage is especially important because that is when first impressions are made it is a challenging period that can affect community relations during the whole mine life cy

cle a positive relationship can lead to the early acquisition of a social license if that is maintained it can create the tolerance and mutual understanding needed to deal with conflicts and different interests during the whole life of the mine the normative components of the social license include the community stakeholder perceptions of the legitimacy and credibility of the mine or project and the presence or absence of true trust these elements are obtained sequentially and are cumulative in building toward the social license the mine or project must be seen as legitimate before credibility is of value in the relationship and both must be in place before meaningful trust can develop these concepts are extended in the following subheading sometimes the social license can transcend approval if an important part of the community and other stakeholders include the project into their identity at this level it is common for the community to become defenders of the mine or project since they consider themselves to be co owners and emotionally involved in the future of the mine or project the license is granted by the community a term used generically to describe the network of stakeholders that share a common interest in a mining or exploration project and make up the granting entity use of the terms community and stakeholder network implies that the license is not granted by a single group or organization it is a collective approval granted by a network of groups and individuals therefore the existence of a handful of supporters in the middle of a larger network of opponents would mean that the license has not been granted however the condition that the license be a sentiment for a very different group of individuals originates great complexity into the process in this sense individuals and groups will cooperate with the company for many reasons including courtesy a desire for gain a perception of having no alternative or as is common in many cases a sense of obligation with authorities cooperation for these motives does not indispensably need a confidence relationship 7 3 1 phases of earning a social license as aforementioned a social license has distinguishable levels at the same time the process of moving from one level to another can be thought of as a smooth gradient of continuous relationship improvement through increasing social capital figure 7 9 shows the four levels of social license and the three boundary criteria that separate them the levels represent how the community treats the company the boundary criteria depict how the community opines on the company principally based on the behavior of the company the levels and boundary criteria are organized in a hierarchy and it is possible to go both up and down the hierarchy for example if a company loses legitimacy the project will be shut down if full trust is gained the community will support and protect the project as its own starting from

the base the rejection level of a social license is the worst case scenario this is when the community stops progress on the project many mineral deposits cannot be exploited because the community does not grant any level of social license to proceed the withholding withdrawal level is shown as narrower than the acceptance level above it in order to symbolize the possibility that globally more projects are accepted than rejected regarding legitimacy boundary criterion legitimacy can be defined in the context of stakeholders and politics as the approval by the individuals and by relevant organizations of an association s right to exist and to pursue its affairs in its selected way knoke 1985 this adequately summarizes the bare minimum of legitimacy even when the company has no social license where legitimacy is established the community response is that they will listen to the company and consider its proposals if by their own standards they have no reason to doubt the company s credibility they can allow the project to tentatively proceed this constitutes the acceptance level of social license it is a minimal objective for any company the acceptance level is bounded by the legitimacy criterion and the credibility criterion this represents how acceptance requires that the company s legitimacy must be firmly established and its credibility should at least not be damaged legitimacy can be earned by just listening credibility requires doing something about what has been heard credibility is the basis of confidence and where an enterprise is considered as credible it is seen as following through on promises and dealing with everyone an essential component of credibility comes from openness and transparency in the provision of information and decision making where a company has established both legitimacy and credibility a community is likely to grant approval of the project this means the company has secure access to the resources it needs the community regards the project favorably and is pleased with it this level of social license depicts lack of sociopolitical risk regarding the full trust boundary criterion in management research trust has been shown to be essential in relationships between and within organizations trust is especially important where bridging the boundary between businesses and civic sector organizations which include many community groups credibility is a basic level of trust related to honesty and reliability communities that have a complete level of trust in a company think that the company will always behave according the interest of the community consequently both parties come to view project s success as a co ownership arrangement the limits of the responsibilities of each party are clear as are ultimate decision criteria at this co ownership level of social license the company becomes an insider in the community social network working closely together the company and communi

ty often develop creative solutions to all types of challenges if outside stakeholders like the national government or an international nongovernmental organization ngo move against the interests of the company the community will mount a campaign in defense of the company there have been cases where community members have traveled to foreign countries to challenge false information being promoted by ngo critics few mining companies have taken their community relations to the co ownership level many have difficulty seeing beyond the immediate transactions to the much greater benefits of establishing strong collaborative relationships nonetheless as awareness of the potential benefits grows more companies are attempting to win a higher level of social license potential environmental issues associated with mining activity such as water use and quality wastes hazardous materials biodiversity noise and vibrations and visual impacts fig 7 10 can take place during all phases of the mining cycle from exploration to closure and post closure phases the issue is that mining involves many stages that commonly begin from deposit prospecting and exploration stage mine development and preparation phase mine exploration stage and treatment of the mineral itself with each of these phases involving specific environmental adverse effects therefore since there are different phases in a mining project each phase of mining is associated with different sets of environmental impacts the adverse effects exploration stage on the natural environment are generally minimum but it is worth initiating surveys of the present state of the environment before starting any activity that will impact the environment thus activities at ground level commonly need the utilization of boreholes pitting and transect lines for example the drilling fluids utilized in diamond drilling can get into the water utilized to bring cuttings to surface this water therefore must be adequately disposed so that it does not pollute the groundwater the application of support equipment also affects the environment since prospecting vehicles request access tracks for this reason application of high standard environmental management procedures in mineral prospection is critical to assure that such activities are adequately managed with the protection of environmentally delicate zones and community concerns efficiently addressed moreover some countries request independent environmental evaluations for the exploration stage of a mining project since subsequent phases of mining cannot assure if prospection fails to find sufficient amounts of high grade mineralization once an ore body of sufficient grade has found then the mining company can start for planning the development of the mine this stage of the mining project has different components and possible environmental adverse effects thus construction works and the greater amount of traffic originate noise and

dust changes to the land surface raise the risk of soil erosion fig 7 11 and surface runoff and the further incremented waterborne loads of solid particles increase the turbidity of water bodies drainage water and runoff from a mine operation can also increment loads of metals and nitrogen in water bodies downstream if water is not adequately controlled all of these changes in water body features as well as in vegetation can affect the conditions for organisms and generate significant changes in species biodiversity on the other hand if a mine operation is situated in a distant undeveloped area the mining company usually requests to start the operations by clearing land for the construction of staging areas that would house project personnel and equipment relative to other phases of activity the design and construction phase is short however this intense group of activities and related environmental implications can be destructive if not carefully managed after the mining company has developed access roads and staging areas mining can begin surficial mining generally includes the extraction of vegetated zones and commonly also includes the generation of an open pit that extends below the groundwater table in this situation groundwater must be pumped out of the open pit to enable mining to develop thus mining operations at this stage originate discharges to water that can represent the most important adverse effects to the environment outflows of water from the mine site can result in changes such as incremented turbidity acidification or salinization in water bodies downstream as well as incremented concentration of metals and nutrients regarding the mining projects that exclusively include removing of abandoned waste piles they prevent the environmental adverse effects of surficial mining but still imply environmental impacts linked to concentration of minerals and or metals from the waste piles underground mining although it is a less environmentally harmful method to extract the mineralization in an ore deposit it is usually more expensive and implies greater safety risks than open pit mining mineralization extraction utilizing specializing heavy equipment such as loaders haulers and dump trucks which transport the ore to concentration installations utilizing haul roads can produce noise and generate a specific group of environmental adverse effects such as emissions of dust finally disposal of overburden and waste rock is also a source of different environmental impacts commonly associated to presence of harmful substances these materials are often located on site either in piles on the surface or as backfilling in pits or within underground operations therefore environmental assessments for mining projects must carefully evaluate the management possibilities and related adverse effects of overburden disposal after the ore has been brought to surface the process of getting the metal out can als

o create harmful substances in beneficiation processes grinding results in tailings that must be designed to avoid harmful components to reach the environment for this reason a treatment procedure for capturing chemically the by products must be included in the design thus they can be safely disposed individually from the principal portion of the mine tailings for example sulfides present in the waste rock have to be kept from creating acid runoff meanwhile different concentration techniques create several types of waste including waste rock dumps another type of tailings heap leach products e g in gold treatment and dump leach products e g in copper leach beneficiation the concentration process uses plenty of water and this water can contain small concentrations of various organic and inorganic reagents used in the concentration process how this high volume of water and material is disposed is one of the central questions that will establish whether a suggested mining project is environmentally suitable the essential long term objective of tailings management is to avoid the release into the environment of toxic components of the tailings for instance wastes including sulfide minerals can produce acidic or neutral runoff with elevated concentrations of metals and sulfates as the sulfide minerals are acidified if water is not adequately managed this can decrease water quality in surface water and groundwater bodies in some cases water flowing from zones where tailings have been disposed can also include traces of chemicals utilized in mineral processing e g flotation another issue of concern is the potential migration of pollutants through rock masses in fracture rocks the main portion of the pollutants can migrate through a system of joins bedding planes and faults producing contamination of soil and groundwater 7 4 2 waste impacts and their management at large mines the mass of mineral waste generated can commonly be measured in tens of millions to billions of tons similarly the surface area that must be disturbed for mineral waste disposal is often measured in tens to thousands of hectares and can account for the main disturbance waste related perpetual water management and treatment can account for more than half of the total closure cost at some mines borden 2011 public concerns during project permitting are commonly centered on potential exposure risks and water quality impacts from chemically reactive mineral wastes and can result in project delays and costly permitting requirements fortunately significant advances in mineral waste characterization and management have been made over the past several decades proactive mineral waste management can significantly reduce the intensity footprint and duration of environmental impacts companies that practice proactive management can reduce their financial liability improve their reputation and become miners of choice helping ensure access

to new mining opportunities the environmental adverse effects of mine wastes are controlled by their type and compositions which change significantly with the raw material being extracted type of mineralization and methods utilized to concentrate the ore as a result each mine needs its own waste profiling prediction monitoring control and treatment most mine wastes are environmentally harmless and can be utilized for landform reconstruction vegetation covers and road and dam construction according to rankin 2011 the main environmental impacts from waste disposal at mine sites can be separated into two categories a the loss of productive land following its conversion to a waste storage area and b the introduction of sediment acidity and other contaminates into surrounding surface and groundwater from water running over exposed problematic or chemically reactive wastes despite the recycling of many waste types at mines the bulk of waste generated is still located into storage facilities and the restoration and long term control of these installations have become an essential part of modern mine development and closure governments and other types of regulators can request any waste storage structures to maintain stable at least for 100 or 200 years which indicate they must withstand utmost events such as floods and earthquakes thus technological improvements and variation in regulations have produced a meaningful enhancement in waste management procedures over the last 10 20 years consequently mine wastes at contemporary mines are usually better managed than they have been in the past moreover governments of many countries request a specific waste management plan before they will issue mining permits guidelines on waste management and mine closure have been created at different levels international national and regional and offer an advisory framework for best practices in mine waste management correct control of tailings and waste rock is based on electing adequate waste storage placements and specific material description including the precise forecasting of long term chemical behavior structures such as waste and tailing dumps and containment facilities must be designed and treated such that geotechnical risks and environmental adverse effects are adequately evaluated and managed throughout the whole mine cycle 7 4 2 1 types of waste solid wastes can be produced in any phase of the mining activity type quantity and features of solid mine wastes originated at diverse mines can change based on the raw material being extracted beneficiation method utilized and geology at the mine site in general the principal types of solid mine wastes are the following 1 overburden cover of soil and rock that is extracted to obtain access to the mineralization at open pit mines overburden usually has a low potential for environmental contamination and is commonly utilized for landscape contouring and reveg

etation during mine closure fig 7 12 2 waste rock material that includes mineralization with low grade considered not interesting to be mined at a profit 3 tailings the fine solid waste generated in the beneficiation process e g froth flotation waste rock is typically a poorly sorted mixture of clay silt sand gravel and boulder sized material although waste rock can be utilized as backfill in earlier mined areas or translated off site and utilized at construction projects most of the waste material originated is placed in piles close to the mine site the most common disposal method for waste rock is placement within dumps and stockpiles although in pit disposal is common in strip mines not all mine wastes are defined as harmful wastes since they can even be utilized as feedstock for cement and concrete such materials cannot be classified as wastes by definition because they really represent meaningful by products of mining operations on the other hand tailings are the fine grained waste that remains after the minerals or elements of economic interest have been removed from the ore fig 6 91 thus tailings are composed of the gangue minerals in the ore and residual minerals of economic interest that were not recovered along with process water and any reagents that were added during the milling and concentration processes tailings commonly leave the process as slurry formed by 40 70 liquid and 30 60 solids they are usually disposed of in the form of a water based slurry in specially engineered repositories on site impoundments such as tailing ponds that are capable of containing the fine grained and often saturated tailings mass without risk of geotechnical failure when developing a waste characterization program operations must identify and understand the physical and chemical characteristics and hazards of all mineral wastes that will be disturbed exposed produced or imported over the life of the operation the characterization program must be rigorous enough to provide reliable predictions of the long term physical and chemical behavior of the waste ultimately the program will be used to select appropriate management strategies that comply with pertinent regulations for each waste type ensure that all repositories are physically and chemically safe and stable and allow for successful rehabilitation and closure borden 2011 the presence of chemically reactive mineral waste can significantly increase the complexity and cost of waste management successful management of chemically reactive mineral waste requires thorough understanding of pertinent regulations well designed characterization programs careful site selection good facility design and rigorous ongoing management and monitoring 7 4 2 2 potential impacts mineral waste disposal can be responsible for much of the environmental impact caused by mining potential impacts that must be assessed minimized and mitigated during mine des

ign operation and closure include the following 1 direct land disturbance construction of out of pit mineral waste storage facilities will typically require burial of the pre mining surface its soils and ecosystems beneath tens to hundreds of meters of waste 2 geotechnical instability unless properly designed thick waste piles can be prone to geotechnical instability and failure instability can range from excessive surface erosion to large deep seated slope failures geotechnical risks are generally highest for tailings and other fine grained waste materials that are saturated when deposited 3 erosion and sediment release erosive wastes are prone to the formation of gullies and other erosion features the release of sediment at much higher rates than surrounding natural landforms can have negative impacts on down gradient surface water bodies and aquatic ecosystems 4 visual impacts large scale mineral waste transport and placement can significantly modify the landscape creating landforms that are taller than the surrounding topography truncating valleys and drainage lines and creating unnatural uniform planar landforms that do not blend in with the surrounding natural topography visual impacts are likely to be a particular concern near population centers and recreational or protected areas 5 direct exposure risks chemically reactive mineral waste can pose direct chemical exposure risks to people plants and animals that live on or near the waste the ph salinity or metal content of the waste can also inhibit vegetation establishment and prevent successful rehabilitation of waste surfaces 6 water quality degradation chemically reactive mineral wastes can degrade the quality of water that runs off or seeps through the waste material unless properly managed this can cause degradation of surface and groundwater quality impacts to aquatic ecosystems and loss of the beneficial use of water resources far from the point of initial waste placement 7 dust release wind erosion and dust release can degrade air quality because of increases in suspended particulate matter if the dust is derived from chemically reactive waste wind transport can disperse potential contaminants over a broad area borden 2011 7 4 2 3 site selection waste disposal facilities should be located in areas that minimize environmental impacts and long term environmental liabilities the selection process should include a review of site regulatory requirements baseline conditions and environmental considerations environmental consequences and direct surface impacts caused by disposal in general the following factors should be considered when selecting locations for waste disposal facilities 1 only place waste within legally permitted areas 2 where practicable preferentially place waste within inactive open pits underground workings or existing disturbed areas 3 avoid permanent disruption of drainage systems 4 tie waste

repositories into the surrounding topography to maintain natural free draining landforms and to reduce visual impacts 5 avoid placement on land with high biodiversity or ecosystem services values 6 avoid placement in areas with significant archeological or social value 7 avoid placement in close proximity to local communities 8 preferentially place chemically reactive wastes in drainage basins that already contain reactive waste thereby avoiding placement in undisturbed drainages 9 limit the footprint of chemically reactive mineral waste to the maximum extent practicable j avoid placement in areas with poor foundation conditions due to topography underlying geology or hydrology 10 avoid placement of chemically reactive mineral waste over significant aquifers or groundwater recharge zones 11 where the choice is available such as in some mountainous terrains preferentially place chemically reactive waste in areas with significantly dryer climates 12 balance economic considerations such as haul profiles potential resource sterilization and pumping costs with environmental social and closure considerations 13 avoid placement in or near perennial surface water bodies or in large ephemeral drainage lines where practicable unless this represents the preferred environmental alternative borden 2011 7 4 2 4 waste rock dump management the overburden and waste rock is commonly arranged in engineered waste rock dumps controlling the dumps during the mine life cycle is essential to protect human health safety and environment according to the international finance corporation from the world bank group icf 2007 the main recommendations for management of waste rock dumps are the following a dumps should be planned with appropriate terrace and lift height specifications based on the nature of the material and local geotechnical considerations to minimize erosion and reduce safety risks b management of potentially acid generating wastes should be correctly undertaken and c potential change of geotechnical properties in dumps due to chemical or biologically catalyzed weathering should be considered reducing the dumped spoils significantly in grain size and mineralogy design of new facilities has to provide for such potential deterioration of geotechnical properties with higher factors of safety 7 4 2 5 tailings management tailings management strategies change based on the site constraints and the nature type of the tailings because tailings are formed of fine particles sand silt and clay sized material and usually including high water content they have been especially problematic to manage thus tailings management planning must take into account how tailings will be operated and placed in addition to continued storage after decommissioning strategies should include the site topography downstream receptors and physical features of tailings e g projected amount grain size distribution

density and water content among others critical considerations for leading practice tailings management are location of the tailings storage facility geochemical characterization of the tailings choice of the best tailings disposal technique tailings delivery water management and dust control fig 7 13 leading practices utilizing paste tailings good water management and correct drainage and liners where adequate would result in completely consolidated tailings for this reason tailings management needs the involvement of competent professionals taking action in accordance with sound geotechnical and hydrological engineering principles the selection of appropriate management strategies typically begins by comparing the impacts as predicted by conceptual or numeric models to environmental compliance and performance objectives if needed a strategy is selected to reduce the potential impacts and ensure that all compliance and performance objectives will be met during start up operation and closure the selected strategy does not have to completely prevent any solute or contaminant release but must ensure that release rates meet regulatory requirements and are low enough to be assimilated by the receiving environment without causing harm to people ecosystems organisms or resources borden 2011 7 4 2 6 monitoring after a mineral waste management strategy is selected and waste storage facilities have been designed they must be constructed and successfully managed on an ongoing long term basis monitoring data should be reviewed regularly and historical trends should be examined so the longer term chemical behavior of the mineral waste can be assessed time series of monitoring data should be maintained so that long term changes in water quality flow rate or other key parameters can be tracked and significant changes can be identified monitoring is required to ensure successful implementation of the mineral waste management plan and to ensure that the strategy is leading to the intended results monitoring reports should be prepared annually and reporting should be accessible easily understood and transparent to stakeholders physical monitoring programs for waste disposal facilities will commonly include at a minimum a regular visual inspections of surface structures and facilities such as spillways fig 7 14 piping dykes ditches and other water management systems b regular visual inspections for signs of excessive surface erosion and shallow or deep seated failure on the outer slopes of waste repositories and c monitoring of water levels and pore pressure within embankments and the waste spillways consist of primary spillways which are designed to allow smaller flows out of the impoundment and emergency spillways which are designed to pass a peak flow and to ensure the stability of the embankment most treatment type reservoirs are designed with both a primary and an emergency spillway so that

treated water can be released on a regular basis while protecting the embankment programs to monitor the geochemical behavior of waste disposal facilities will include a periodic sampling of runoff water fig 7 15 and water discharging from the facility s toe in order to monitor flow volumes solute concentrations and the solute mass that is being released from the waste b periodic sampling of down gradient monitoring wells and surface water bodies to ensure that seepage from the waste is not adversely impacting receiving environment water quality and c periodic assessment of revegetation success such as total cover species composition and plant health water is utilized in mining in a wide rank of operations such as beneficiation processes dust elimination slurry transportation and employee requests the water cycle of a mine is interlocked with the global hydrologic water cycle of a watershed fig 7 16 the mining industry has made significant advances in the last decades in developing close circuit considerations that maximize water preservation in parallel operations are commonly situated in zones where there are not only important municipal agricultural and industrial needs but also diverse opinions about the role of water moreover the local environments of mine operations rank from very low to the highest rainfall zones in the world independently liable management of water by mining enterprises is an essential component to assure that their contribution to sustainable development is clearly positive over the long term in this sense it is necessary to bear in mind that managing water is one of the most important environmental activities at operating mines moreover water control is a collaboratively liability across the operations although collective management does not signify that liability for certain zones cannot be allocated global responsibility is best controlled if the operation has someone in charge of committees and processes the main sources of water on a mine site are from precipitation dewatering of open pits or underground workings and pumping and removal of groundwater specifically around open pit operations precipitation that falls on the mine site must be collected and cleaned prior it can be discharged to the environment water from the dewatered open pit works or underground operations requests to be treated before being released regarding management of water utilized on the mine site e g processing the ore or watering of roadways to keep dust down during dry periods the water is usually recycled so only a small amount of new water is needed every day for example chemicals utilized in the concentration process are generally removed or diluted before tailings are sent to the tailings storage facility planned water releases from mines into the environment are commonly closely controlled to assure observance with legislation and to diminish adverse effect to receiving waters rele

ase of process water is systematically managed and must acquire some quality standards and requests in terms of temperature ph and conductivity other discharges are produced due to normal run off utmost storm events and release from surplus dewatering where water can be contained and discharged appropriately icmm 2012b surrounding surface and groundwater quality is controlled and numerous treatment procedures can be utilized to assure mine water complies legislation standards previous to be released one of the principal issues that can be linked to mining operations is the release of contaminants to surface water since many activities of a mining operation can generate toxic and nontoxic components to surface water thus open pit tailings pond mineralization stockpile waste rock dump and heap and dump leach pile are all examples of possible important sources of toxic pollutants the mobility of the contaminants from these origins is increased by exposure to rainfall seepage from tailing dump zones and groundwater generating from open pit mines are another examples by which heavy metals can be mobilized and sometimes released to surface waters discharge of contaminants to surface waters can also take place indirectly via groundwater that has hydrological connecting to surface water some adverse effects to surface waters include the buildup of sediments that can be polluted with heavy metals short and long term decreases in ph level especially for lakes and reservoirs degradation of aquatic habitat and contamination of drinking water and other human health issues the impacts of the mining operations to the surrounding water resources and water dependent ecosystems are by water withdrawal and dewatering impacts and the discharge of contaminated water surface and groundwater withdrawals to dewater the ore body or to supply operations can lower surrounding groundwater water tables causing seeps springs and wells to dry up harming groundwater dependent vegetation and ecosystems and reducing in stream flow if necessary dewatering impacts must be predicted monitored and mitigated mitigation strategies can include a improving water efficiency through process and management improvements so that less water needs to be withdrawn b intentional surface water discharge at key locations to maintain in stream flow c providing alternative water resources for impacted communities d intentional recharge of groundwater to minimize drawdown impacts and e construction of slurry walls and other subsurface flow barriers to minimize hydrogeologic connections borden 2011 to reduce these issues an adequate water management plan wmp is essential to leading practice water management its size and complexity is varied depending on the nature of the mine hydrology and cultural and environmental sensibility of the surrounding area the wmp defines all water management problems linked to development operation and decom

missioning a project integrating also water quantity and quality the wmp records particular site water goals against which performance can be assessed quantitative aims are better for an efficient auditing of performance the wmp also includes any request for internal and external reporting of water performance finally the wmp is dynamic and should be systematically updated and reviewed commonwealth of australia 2008 7 4 3 2 practices for water management water treatment before discharge can be costly at large mines with significant acid rock drainage flows cumulative treatment costs can be measured in the tens to hundreds of millions of dollars implementation of internal proactive management strategies that reduce the volume of water that must be treated and or reduce the solute load in the water can be cost effective as well as ultimately more protective of the environment borden 2011 broad water management strategies and control techniques to decrease the potential for water pollution and diminish the amount of water needing treatment include the following a water diversion capture and diversion of clean surface and groundwater flows up gradient of the operation can limit the volume of water that can be contaminated by contact with the operational footprint b improved water use efficiency improvements in water use efficiency can also reduce the volume of water that must be imported into the operation c reagent management process water quality can be improved by the efficient use of reagents and or replacement of hazardous reagents with less hazardous but equally effective substitutes d on site evaporation evaporative losses within the footprint of the operation will reduce the volume of water that must be discharged and e installing liners and covers on waste rock and ore piles to reduce the potential for contact with precipitation and contamination of groundwater lottermoser 2012 different combinations of strategies can be applied and the selection of strategies is site specific for instance the interception and diversion of surface water is a more prominent concern in environments with high rates of precipitation whereas more emphasis is placed on water recycling in arid regions with little water availability for water treatment there are numerous treatment methods forthcoming to clean contaminated water being these technologies classified as active or passive active treatment methods need input of energy and chemicals while passive technologies use only natural procedures such as gravity microorganisms and or plants in a system anyone of which requests uncommon but regular maintenance younger et al 2002 in general the treatment methodology utilized at a mine is based on how contaminated the water is what chemicals products require to be extracted how much water needs processing and the needed release water quality standards active water treatments are the most usual manner of water

processing at working mines fig 7 17 thus mine waters are almost always acidic and need the addition of lime or caustic soda to increase the ph once ph has been incremented dissolved metals can precipitate out of solution and sink to the bottom of settling or sedimentation ponds where they can be extracted chemicals called coagulants or flocculants can be added with the aim of converting smaller particles into larger clumps that settle out of the water more quickly brown 2002 regarding the passive water treatments they are commonly combined with water monitoring programs and advantage of natural physical chemical and biological processes that remove water contaminates without additional physical or chemical inputs examples of these procedures are bacteria controlled metal precipitation contamination uptake by plants and filtration through soil and sediments the term acid mine drainage amd or acid rock drainage ard is used to describe the drainage resulting from the natural oxidation of sulfide minerals that occur in mine rock or waste exposed to air and water it is important to remember that it is a natural process not something specifically generated by mining box 7 4 chemistry of acid mine drainage amd can incorporate acidity and dissolved metals into water which is usually very harmful to aquatic life acid mine drainage is responsible for problems of water pollution in major coal and metal mining areas around the world once amd develops it can be hard to control and stop if acid mine drainage is not controlled it can pose a serious threat to the environment because acid generation can lead to elevated levels of heavy metals and sulfate in the water which obviously have a detrimental effect on its quality stopping amd development can be very complex since it is a process that when left unrestrained will advance and can accelerate until some of the chemical components sulfide minerals oxygen and water are depleted or removed from reaction verbug 2011 thus the development of ard is time dependent and sometimes can evolve over a period of decades or even centuries after mining has ceased managing acid rock drainage is a preoccupation at mine workings and after mine closure furthermore amd is also a major concern for mining companies since nowadays mining operations tend to increment the quantity of rocks exposed to air and water and many metal mineralization and coal deposits are rich in sulfide minerals in this sense mining companies are upwardly requested to assess the ard potential at future mine operations and propose comprehensive planning to prevent or avoid ard at all stages of mining cycle as part of the environmental impact assessment eia procedure the process of sulfide oxidation and development of amd is not easy to understand and includes numerous chemical and biological processes that can change importantly in accordance with environmental geological and climate characte

ristics nordstrom and alpers 1999 in unaffected natural situations acid development is a moderately slow process considering geological time but mine works and concentration of mineralization and materials incorporating metal sulfides hugely increase the acid generating process because it rapidly exposes those substances to oxidizing conditions the most common acid generating sulfide minerals are pyrite fes2 pyrrhotite fes marcasite fes2 chalcopyrite cufes2 and arsenopyrite feass it is clear that not all sulfide minerals originate acidity when being oxidized since sphalerite and galena tend not to generate acidity when oxygen is the oxidant but it is also very evident that all sulfide minerals are capable of generating acidity if aqueous ferric iron is the oxidant in this sense the presence of microorganisms such as thiobacillus ferrooxidans may accelerate the reaction by its enhancement of the rate of reduced sulfur oxidation if conditions are not favorable the bacterial influence on acid generation will be minimal as aforementioned ard is a natural process and has been produced in a natural manner over millions of years thus the names of rivers such as the rio tinto in spain the norwegian raubekken and the iron creek in colorado reflect the historical nature of amd in general ard can show the following chemical features a low ph ranging from 1 5 to 4 b high soluble metal concentrations c high sulfate salinity d low quantities of dissolved oxygen and e low turbidity or total suspended solids on the other hand according to commonwealth of australia 2007a essential indicators of amd presence include red colored fig 7 18 or unnaturally clear water orange brown iron oxide precipitates in drainage lines death of fish or other aquatic organisms precipitate formation on mixing of amd and background receiving water poor productivity of revegetated areas e g waste rock pile covers vegetation dieback e g bare areas and corrosion of concrete or steel structures for instance the most common and very noticeable manifestation of ard from a dump is the reddish brown staining associated with the effluent and which consists of precipitates of principally ferric salts these salts are a source of turbidity but they do not represent an environmental issue locations susceptible to develop acid rock drainage since sulfides can be routinely exposed to air and water are waste rock pile ore stockpile tailings storage facility fig 7 19 underground mine and heap and dump leach pile however ard will not occur if the sulfide minerals are nonreactive or if the rock contains sufficient alkaline material to neutralize the acidity in the latter instance ph value of the water may be near neutral but it may carry elevated salt loads especially of calcium sulfate in other words the acid generating capability of sulfide minerals is countered by acid neutralizing minerals most carb

onate minerals are capable of dissolving quickly making them efficient acid consumers in some cases calcium magnesium silicates can buffer mine effluents at neutral ph in cases of near neutral ph the levels of major ions such as calcium magnesium and sulfate are unacceptably high from an environmental viewpoint however the neutralization of acid generally increases the amount of toxic metal concentrations in the resulting drainage while increases in ph are desirable the consequent increase in toxic metal concentrations is not at most mining sites there is not sufficient natural neutralizing materials to increase the ph of drainage to near neutral values thus acid mine drainage characterized by low ph and high toxic metal concentrations is the most usual manner of amd undergone at mine operations commonwealth of australia 2007a lottermoser 2012 affirms that the rate of amd generation depends on a number of factors such as 1 surface area of sulfide minerals exposed increasing the surface area to air and water increases sulfide oxidation and amd formation 2 type of minerals present not all sulfide minerals are oxidized at the same rate and neutralization by other minerals present can occur which would slow the production of amd 3 amount of oxygen present sulfide minerals oxidize more quickly where there is more oxygen available as a result amd formation rates are higher where the sulfides are exposed to air than where they are buried under soil or water 4 amount of water available cycles of wetting and drying accelerate amd formation by dissolving and removing oxidation products leaving a fresh mineral surface for oxidation in addition greater volumes of amd are often produced in wetter areas where there is more water available for reaction 5 temperature pyrite oxidation occurs most quickly at a temperature around 30 c 6 microorganisms present some microorganisms are able to accelerate amd production important progresses in the knowledge of amd have been carried out in the last decades with advancements also in mine water quality forecast and utilization of preventing methods however mine water quality forecast can be complex due to the broad range of the chemical reactions included and potentially very long periods over which these reactions develop in spite of the uncertainty quantitative forecasting generated by utilizing realistic scenarios has demonstrated to be of significant value for identifying amd management options and evaluation of potential environmental adverse effects thus prediction of mine water quality generally is based on one of more of the following procedures a test leachability of waste materials in the laboratory b test leachability of waste materials under field conditions c geological hydrological chemical and mineralogical characterization of waste materials d geochemical and other modeling amd is one of the most sensible and visible environmental

problems facing the mining industry because it is often the method of transport for a rank of contaminants which can affect on site and off site water resources and associated human and ecological receptors the impacts of amd on near and distant water resources and receptors can also be long term and persist after mine closure therefore amd prevention mitigation and treatment are important components of overall mine water management over the entire life of a mining operation verbug 2011 the environmental adverse effects of amd depend on the size and sensibility of the water body concerned and the quantity of neutralization and dilution for instance the same amount of ard would have greater adverse effect on the water quality of a small lake than it would have in the ocean as the ocean has a higher dilution capability and salt water has stronger acid buffering capacity than freshwater the dissolved metals associated with amd are commonly more toxic to fish and aquatic organisms than is the acidity 7 4 3 3 3 amd prediction and mitigation one of the most important studies that must be carried out in a mining environmental assessment is to evaluate the potential developing of amd processes thus an accurate prediction of acid mine drainage is required in order to determine how to bring it under control the objective of amd control is to satisfy environmental requirements using the most cost effective techniques the options available for the control of contaminated drainage are greater at proposed rather than at existing operations as control measures at working mines are limited by site specific and waste disposal conditions the length of time over which the control measurements are requested to be efficient is a factor which requires to be determined previous to the design of a system to control ard the prediction of the potential for acid generation involves the collection of available data and the performance of static and kinetic tests both tests provide data that can be used in different models to predict the effect of acid generation and control processes on the other hand a risk based planning and design forms the basis for prevention and mitigation of amd the main goal of the risk based procedure is to quantify the long term adverse effects of alternatives and to utilize this knowledge to elect the option that has the most convenient combination of attributes including the prevention and mitigation effort into the mine operation is an essential factor for successful amd management inap 2009 therefore the most cost effective and low risk amd management approach is to prevent amd development through prediction and mine planning prevention of amd must begin at exploration stage and continue throughout all the mine cycle being the keystone to avoid costly mitigation the first aim is to use techniques that minimize sulfide reactions metal leaching and further migration of weathering products originated from su

lfide oxidation where sulfide mineral extraction is inevitable a number of amd prevention strategies have been carried out such as locating waste rock underwater flooding and sealing underground mines mixing acid producing materials with acid buffering materials covering waste rock and treating of sulfide wastes chemically in the latter organic chemicals have been used to sulfide wastes with the aim to decrease the rate of amd however there is concern that some of these chemicals can reduce beneficial microorganisms in the environment thus being pollutants themselves price and errington 1998 johnson and hallberg 2005 in this sense it is far more efficient and usually far less costly in the long term to control acid mine drainage during its early phases prevention and control of amd is undertaken using primary secondary and tertiary control mechanisms primary control measures are those that prevent amd from developing they commonly include segregating potentially acid origination waste rock or tailings from non potentially acid generating rocks and locating it underwater or underground secondary control measures are those that do not stop amd from developing but prevent or decrease the migration of amd waters in some cases secondary control measures can be applied until primary methods can be developed finally tertiary control measures involve the long term collection and treatment of amd waters to decrease acidity and remove dissolved metals this is an unacceptable solution for a new mine and is only utilized for old or closed mines that did not consider amd mitigation at the time of the operation or were not planned effectively this type of measures is costly and can go on indefinitely stevens 2010 obviously where the entire prevention of amd process is ineffective acid mine waters must be trapped and treated utilizing a number of water treatment processes 7 4 3 3 4 amd management the management of amd and the evaluation of its efficiency are generally considered within the site environmental management planning or in a site specific ard management report the requirement for a formal amd management planning is commonly motivated by the results obtained in amd characterization and prediction reports or the results of site monitoring it is important to note that the development evaluation and constant enhancement of an amd management planning are a continuum throughout the life of a mine inap 2009 the principal objective of the management planning must be to minimize or wherever possible remove the footprint of potentially acid forming materials the amd management planning detects materials that need special management to be efficient the amd management planning must be completely integrated with the mine plan finally accountability to implement the management planning is verified to assure that those responsible are meeting the requests stipulated in the plan strategies to manage ard can be classi

fied in three main types minimization of oxidation and transport of oxidation materials control to decrease contaminants and or active or passive treatment to enable water reuse from a sustainability point of view minimization is favored to control and the latter is preferred over treatment election of the best minimization and control management strategies depend on climate topography mining method material type soil rock types mineralogy and available neutralization resources as well as interrelationships between these the control of acid mine drainage can request different approaches depending on the severity of potential acid generation the longevity of the source of exposure and the sensitivity of the receiving waters regarding treatment of waters there are two phases involved with the design of a system for the treatment of acm one during mine operation and another after closure in any case conventional active treatment of mine waters needs the installation of a treatment plant continuous operation and maintenance which result in high capital and operational costs alternatively passive methods try to minimize the inputs of energy materials and manpower and so decrease operational costs sulfide minerals in ore deposits are former under reducing conditions in the absence of oxygen when exposed to atmospheric oxygen or oxygenated waters due to mining mineral processing excavation or other earthmoving processes sulfide minerals can become unstable and oxidize thus the generation of acid h occurs typically where iron sulfide minerals are exposed to both oxygen from air and water this process can occur both abiotically or biotically e g microorganisms in the latter case bacteria such as acidithiobacillus ferrooxidans which derive their metabolic energy from oxidizing ferrous to ferric ion can accelerate the oxidation reaction rate by many orders of magnitude relative to abiotic rates sulfide oxidation produces sulfuric acid and an orange precipitate ferric hydroxide fe oh 3 there are two key processes involved in the generation of acid h from iron sulfide a oxidation of sulfide s2 2 to sulfate so4 2 and b oxidation of ferrous iron fe2 to ferric iron fe3 and subsequent precipitation of ferric hydroxide once sulfides have been oxidized to sulfates it is difficult to avoid oxidation of aqueous ferrous iron to ferric iron and subsequent iron hydroxide precipitation this precipitation stage is acid generating reaction 1c the interaction between dissolved ferric iron fe3 and fresh iron sulfide minerals can also lead to significant acceleration of the acid generation processunder the majority of circumstances atmospheric oxygen acts as the oxidant however aqueous ferric iron can oxidize pyrite as well this reaction is considerably faster two to three orders of magnitude than the reaction with oxygen and generates substantially more acidity per mole of pyrite oxidiz

ed however this reaction is limited to conditions in which significant amounts of dissolved ferric iron occur i e acidic conditions ph 4 5 and lower oxidation of ferrous iron by oxygen is required to generate and replenish ferric iron and acidic conditions are required for the latter to remain in solution and participate in the ard production process 7 4 4 hazardous materials management hazardous substances are materials that can have adverse effect on human health due to their physical chemical and biological properties common hazardous industrial wastes include solvents used oil oily debris spent reagents coolants greases batteries and used paints usually these wastes are sent to off site recycling treatment or disposal facilities taken into account the previous definition some materials found in mining and processing operations can be hazardous to human health and the environment naturally occurring materials that can be classed as hazardous when exposed by mining include asbestiform minerals silica metals and radioactive minerals chemical substances utilized in mining e g explosives and flotation reagents are hazardous as well wastes and by products of mining operations such as dusts and acid generating sulfides can also be hazardous the actual risks posed by the handling of these materials depend on their innate hazards volumes that are present potential receiving environments and transport pathways that could connect the point of release with potential receptors borden 2011 7 4 4 1 asbestiform minerals where asbestiform minerals are found table 7 1 airborne asbestos fibers can be present as minor trace contaminants in the dust produced during blasting crushing and further handling and processing concern about the effect on health from long term low level exposure to asbestos needs that adequate procedures be used wherever asbestiform minerals are encountered the aim is to assure that exposure is as low as is acceptably suitable to minimize the potential risks from asbestiform material a competent person such as a geologist or mineralogist should analyze exposed rock during the initial studies into the ore body to determine the presence and extent of asbestos an asbestos management planning can then be prepared for the risk zones determined through asbestos exposure monitoring silica minerals make up the matrix or occur linked to the targeted mineral in mineralization they include quartz which is a common gangue component of the ores and a very common rock forming mineral in most igneous and metamorphic rocks the same natural process that results in sulfide ore bodies often concentrates silica minerals they are stable until ground or blasted into a dust crystalline silica dust is termed as a group 1 carcinogen by the international agency for research on cancer being the dust irritant to lungs 7 4 4 3 metals metal concentrations increment in waters at low ph values thus d

issolved metals can move from mining facilities to local ground and surface water once released metals will continue in the environment while amd can improve pollution mobility by fostering leaching from wastes and mine infrastructures liberations can also take place under neutral ph values first sources of metals in solution from mining works cover underground and surface mine operations overburden and waste rock piles tailings piles discharges from beneficiation processes leach piles and processing facilities chemical disposed areas and restoration activities thus depending on the local geology the mineralization and the waste rock and overburden can contain trace levels of numerous elements such as arsenic cadmium chromium copper iron lead mercury nickel silver zinc and many others as well as naturally occurring radioactive materials the presence of certain metals their liberation potential and the linked risks are very dependent on facility specific features such as design and operation of mining and mineral processing operations waste controlling methods treatment mitigation measures environmental characteristics e g climate hydrogeology or mineralization composition and geochemistry and nature of and vicinity to human and environmental receptor to prevent the unintended presence of these metals dissolved metal concentrations in water can be decreased through physical removing sorption precipitation and biological uptake all minerals contain radionuclides that are members of the naturally occurring radioactive decay chains the impact of these radionuclides needs to be considered in certain types of mining radionuclides such as uranium thorium radium and radon can pose exposure risks because of toxicity and or radiological hazards igneous and certain metamorphic rocks are more radioactive than most sedimentary rocks the release of uranium and its daughter products are an issue at uranium mines however radionuclides can also pose hazards at heavy mineral sands rock phosphate coal rare earth ore bodies and ore bodies associated with granitic rocks exposure to elevated radioactivity levels can also occur during rare earth production bauxite production and oil and gas extraction among many examples the level of possible hazard from radioactive minerals relies on the type of radioactivity and its half life period one of the major radiological risks in mining is associated with inhalation of radon a radioactive gas with a short half life and its short lived radioactive decay products radon is produced by the radioactive decay of radium radon exposure can be a particular concern at some underground uranium mines and needs to be carefully considered the control of radon at underground uranium mines should commence with the process of selecting the mining method controlling water inflows and designing a flexible ventilation system in addition each mine has to establish safety o

perating procedures specific for each operating mine the latter is extremely important as even the best ventilation system can malfunction because of a power outage human error or other unforeseen circumstances when designing ventilation systems for underground uranium mines deposits can be divided into two groups low grade deposits usually ranging from 0 1 to 2 u3o8 and high grade deposits where the grade can exceed 20 u3o8 apel and hashisho 2011 in the case of high grade deposits the radon emanation rate from the ore would make it practically impossible to dilute the radon daughters using flush through ventilation and in these cases the ore is mined using remote mining methods e g raise boring or mining using water jets regarding management of hazardous materials it starts with their adequate identification during pre feasibility studies followed by characterization of the mineralization waste rock overburden mine process residues and natural soil under the mine installation if harmful naturally occurring minerals are found during mining activities should finish until hazard has been adequately assessed and corrective actions have been organized other hazardous substances utilized and produced on mine and mineral processing sites can include the following 1 acids sulfuric hydrochloric contact with strong acid liquids or fumes is a human health hazard and can also cause structural damage in a facility 2 sodium cyanide for gold recovery in large operations the risk of cyanide poisoning arises from ingestion and exposure to workplace vapors and solutions 3 mercury for gold recovery in small artisanal operations 4 metals as ions or complexes from cu pb zn ni fe as hg and cd sludges or solutions 5 thiosulfates and polythionates also resulting from acid mine water or processing solutions 6 process reagents acids alkalis frothers and collectors modifiers flocculants and coagulants that contain aluminum and iron salts and organic polymers 7 nitrogen compounds from blasting materials best practice consists of adequate ventilation and monitoring of the workplace atmosphere rather than the use of personal protective equipment 8 oil and fuel used for engines power plants and lubrication 9 solvents used in extraction plants commonwealth of australia 2009a 7 4 5 mining and biodiversity the protection and conservation of biodiversity is crucial to sustainable development the united nations convention on biological diversity defines biodiversity as the variability among living organisms from all sources including inter alia terrestrial marine and other aquatic ecosystems and the ecological complexes of which they are part this includes diversity within species between species and of ecosystems thus biodiversity is commonly defined at three separate levels genetic diversity species diversity and ecosystem diversity it is crucial that all partners constituting th

e mining industry admit that biodiversity has significant environmental social and cultural value mining can affect biodiversity throughout the life cycle of a project both directly and indirectly direct or early adverse effects from mining can be produced from any activity that includes land clearance e g access road or tailings dumps construction or direct discharging to water bodies e g riverine tailings disposal or the air e g dusts or smelter emissions this type of adverse effects is commonly easy to identify indirect or secondary impacts can be generated from social or environmental variations produced by mining operations and are usually very difficult to identify quickly icmm 2006 at the same time the mining industry has offered considerable effort to the knowledge of biodiversity management it is essential that the mining industry admits that it not only has a liability to control its impacts on biodiversity but also has the possibility to carry out a decisive contribution to biodiversity conservation through the production of knowledge and the implementation of actions in cooperation with others partners since mining will often have unavoidable negative impacts on biodiversity it is possible to offset impacts by creating benefits elsewhere to produce an overall conservation outcome that maintains the biodiversity assets of a region such offsets can be direct through acquiring comparable land and managing it for biodiversity conservation this process is sometimes referred to as biobanking csiro 2014 another form of a direct offset is through funding the implementation of regional conservation plans biodiversity offsets can also be indirect such as by conducting relevant research for improved conservation management or through education and training that increases regional capacity for biodiversity management the risks and impacts to business of the failure to correctly manage biodiversity problems can include a increased regulation and liability to prosecution b increased rehabilitation remediation and closure costs c social risks and pressure from surrounding communities civil society and stakeholders d restricted access to raw materials including access to land both at the initial stages of project development and for ongoing exploration to extend the lifetime of existing projects and e restricted access to finance and insurance commonwealth of australia 2007b thus it is very interesting for mining companies to address biodiversity for many different sound business reasons consequently most mining companies have established an ever more complex perspective to managing biodiversity as part of their compromises to achieve and maintain a social license to operate taking responsible decisions regarding to biodiversity management is upwardly considered as very important with respect to a reputation which links to the license to operate an intangible but significant benefit

to business it can profoundly influence the perceptions of communities ngos and other stakeholders of existing or proposed mining operations and b access to capital particularly where project finance is to be obtained from one of the investment banks that are signatories to the equator principles which apply the biodiversity performance standard of the international finance corporation ifc to all investments in excess of us 10 million recognizing that strengthened commitments to biodiversity assessment and management are likely to be adopted icmm 2006 the conceptual approach adopted for a good practice guidance is illustrated in fig 7 21 showing how integrate biodiversity into the mining project cycle habitat alteration is one of the most significant potential threats to biodiversity associated with mine operations although this alteration can take place at any stage of the mine cycle there is no doubt that the greatest potential for temporary or permanent alteration of terrestrial and aquatic habitats occurs during construction and operational activities to integrate conservation requests and development priority in a manner that meets the land utilization requirements of local communities is generally a critical problem for mining projects recommended strategies to solve these issues from the international finance corporation world bank group include consideration of the following ifc 2007 1 whether any critical natural habitats will be adversely impacted or critically endangered or endangered species reduced 2 whether the project is likely to impact any protected areas 3 the potential for biodiversity offset projects e g proactive management of alternative high biodiversity areas in cases where losses have occurred on the main site due to the mining development or other mitigative measures 4 whether the project or its associated infrastructure will encourage in migration which could adversely impact biodiversity and local communities 5 consideration of partnerships with internationally accredited scientific organizations to for example undertake biodiversity assessments conduct ongoing monitoring and manage biodiversity programs 6 consultation with key stakeholders e g government civil society and potentially affected communities to understand any conflicting land use demands and the communities dependency on natural resources and or conservation requirements that can exist in the area regarding terrestrial habitat alterations they must be diminished as much as possible and be consistent with the request to preserve critical habitats some controlling strategies include siting access roads in places that prevent adverse effects to critical terrestrial habitat diminishing disruption to vegetation and soils and implementing mitigation techniques adequate for the type of habitat other strategies are preventing the generation of barriers to wildlife movement and offering alternative mig

ration routes if the generation of barriers cannot be avoided and manage vegetation growth along access roads and at continued above ground facilities ifc 2007 aquatic habitats are affected through variations in surface water and groundwater flows and generating incremented pressures on fish and wildlife communities in particular aquatic habitats in marine environments can be affected by several methods to extract resources such as dredge mining and deep sea mining or other activities such as offshore loading activities port development and tailings disposal assessment and control of adverse effects for marine environments must be in accordance with suitable host country obligations to international decisions such as the united nations convention on the law of the sea ifc 2007 to an adequate management of potential affections in aquatic habitats it is essential to maintain water body catchment zones equal or comparable to predevelopment features preventing stream channel stability by restricting in stream and bank disturbance and constructing maintaining and reclaiming watercourse crossings that are stable and safe for the intended utilization and that decrease erosion mass wasting and degradation of the channel or lake bed the provision of an adequate air environment to promote the health safety and comfort of people has always been and will continue to be an essential requisite for successful mining operations airborne emissions can take place during all stages of the mine cycle but specifically during exploration development construction and operation activities the main sources of these contaminants are dust from blasting crushing ore exposed surfaces such as tailings facilities stockpiles waste dumps haul roads and infrastructure and to a lesser extent gases from combustion of fuels in equipment fig 7 22 therefore although dust is the principal emission associated with mines a rank of gaseous and particle emissions are linked to mining and other on site processing operations the adverse effects of air emissions depend on the type of pollutant its release features and the nature of the receiving environment the pollutants can be present in solid liquid and gaseous forms gaseous emissions generated by fuel combustion or mineral processing include pollutants such as sulfur dioxide and nitrogen dioxide that have well defined harmful effects and are tightly controlled in the ambient environment and workplace commonwealth of australia 2009b since management of air quality at mine operations is essential at all phases of the mine cycle dust emissions from the dry surfaces of tailings facilities waste dumps stockpiles and other exposed areas should be always minimized the sequence of dust control techniques are a prevention of generation of dust and its suspension in air b suppression of airborne dust on site c collection of dust that could not be suppressed and d dilution with auxili

ary and main ventilation the control strategy for these environmental impacts depends on the type of contaminants their sources and rates of emission it can range from simple dilution with ventilation air to complex procedures for removal of the contaminant prior to mixing with the mine air or suppression elimination at the source thus the international finance corporation ifc 2007 recommended the following air pollution management strategies 1 dust suppression in roads and work areas optimization of traffic patterns and reduction of travel speeds 2 exposed soils and other erodible materials should be revegetated or covered promptly 3 new areas should be cleared and opened up only where absolutely necessary 4 surfaces should be revegetated or otherwise rendered non dust forming when inactive 5 storage for dusty materials should be enclosed or operated with efficient dust suppressing measures 6 loading transfer and discharge of materials should take place with a minimum height of fall and be shielded against the wind 7 conveyor systems for dusty materials should be covered and equipped with measures for cleaning return belts 8 chemical treatment at haul roads 9 selection of superquality mine explosives 10 installation of dust gas extraction systems at crushers 11 spraying waste rock piles with sealants 12 storing crushed ore that is waiting to be processed in the mill in enclosed structures 7 4 6 2 noise and vibration noise is an inherent health hazard in mining industry raw material exploration extraction and processing can generate important levels of noise that can affect the surrounding environment this is because the mining process is highly mechanized from the earliest ore removal to final processing and heavy equipment is essential at virtually every stage of operation thus exposure to noise is a concern for workers who drive mechanized equipment as well as those who operate or work near stationary equipment such as haulage belts or crushing equipment moreover communities can suffer noise and vibration adverse effects from mining operations in many forms not only from the mine site noise can take place at all stages of the logistics chain including rail and truck haulage and activities at ports commonwealth of australia 2009b exposure to noise levels above regulatory or recommended limits can result in hearing loss it is important to emphasize that most hearing loss is preventable prevention can be achieved by eliminating noise sources substituting quieter equipment installing appropriate engineering controls implementing administrative controls using personal protective equipment and adopting effective hearing conservation programs walter 2011 good practices in management of the noise sources must be defined based on the prevailing land utilization and the vicinity of noise receptors such as communities or community use areas where necessary noise emissions mus

t be managed fig 7 23 through the application of methods that can include a implementation of enclosure and cladding of processing plants b installation of proper sound barriers and or noise containments with enclosures and curtains at or near the source equipment e g crushers grinders and screens c installation of natural barriers at facility boundaries e g vegetation curtains or soil berms and d optimization of internal traffic routing particularly to minimize vehicle reversing needs reducing noise from reversing alarm and to maximize distances to the closest sensitive receptors the most significant vibrations are usually associated with blasting activities in this sense the increasing size and depth of open pit mines and large diameter long hole blast in underground mines further aggravate the vibration haldar 2013 however vibrations can also be generated by many types of equipment measurement and control of vibration serves two purposes 1 prevention of premature wear and failure due to structural damage and 2 reduction of noise levels measurement of vibration requires specialized equipment and experience in data interpretation 7 4 7 other potential environmental impacts 7 4 7 1 subsidence subsidence of the ground surface can be considered as ground movement caused by the extraction from underground of any resource whether it be solid liquid or gas it is commonly an inevitable consequence of such activities and reflects the movements that occur in the area so affected the problems associated with subsidence have been recognized since antiquity agricola s de re metallica of 1556 talks about a mountain or hill subsiding by its weight as a result of mining the subsidence effects of mining raw materials are controlled by the type of mineral deposit the geological features specifically the nature and structure of the overlying rock or soil and the mining method applied in the extraction process in addition time when subsidence occurs depends upon the type of mining as does the reliability of subsidence prediction thus the major objectives of subsidence engineering are prediction of ground movements determining the effects of such movements on structures and renewable resources and minimizing damage the surface displacements and deformations characteristic of subsidence will affect any use made of the ground surface consequently subsidence can generate serious effects on surface structures buildings and communications and can affect agricultural land through the disturbance of drainage and alteration of gradient the creation of any subsurface opening produces deformations and displacements of the material and these changes can cause the rock around a mine excavation to collapse into the mined void the ground movements associated with such collapse tend to propagate to the ground surface with the deformations and displacements experienced there being termed subsidence surface

subsidence generally entails both vertical and lateral movements and can be discontinuous steps cracks or cavities form at the surface or continuous the surface deforms smoothly discontinuous subsidence is generally of limited areal extent and is characterized by large vertical displacements it occurs where material overlying an extraction zone collapses into the void and its form depends on the mining method the geometry of the extraction zone and the geomechanical properties of the rock above the extraction zone harrison 2011 the presence of weak structural features e g faults or boundaries between different geological materials can lead to plug subsidence in which a large plug of material falls suddenly and instantly downward into the mine void the speed and suddenness of the process means this is particularly dangerous mining methods such as block caving and sublevel caving also lead to discontinuous subsidence but in these operations use of an access to the surface area affected by the subsidence is generally prohibited in the case of continuous subsidence above laterally extensive extraction zones such as longwall coal mining operations observations of subsidence profiles or troughs above the mined areas have shown that they can be characterized on the basis of shape in particular the absence or presence of an essentially horizontal central region regarding the factors affecting mine subsidence experience has revealed that many geological and mining parameters besides the width of the extraction zone can affect the magnitude of subsidence the number and interrelation of these factors means that predicting in an accurate quantitative manner the magnitude and time to subsidence onset is generally not straightforward the main factors are the following 1 extraction thickness the thicker the material mined the larger the quantity of possible surface subsidence 2 mining depth magnitude and time to onset of subsidence are dependent on depth 3 inclination of extraction horizon asymmetric subsidence occurs where the zone being mined is inclined 4 degree of extraction reducing the amount of material extracted will reduce the amount of subsidence 5 mined area the critical width of a mined void must be exceeded in all directions if maximum subsidence is to develop 6 method of working the amount of subsidence is largely controlled by the degree of caving induced by the mining method e g complete subsidence for block caving and longwall mining and zero for room and pillar together with the amount of support offered by any backfilling 7 competence of surrounding materials because subsidence propagates from the mine level the mechanical behavior of the rock adjacent to the mined void directly affects the initiation of subsidence 8 geological discontinuities the existence of faults can increase and localize subsidence potential so strongly that in areas of adverse geological conditions the

effects of the other parameters can be discounted 9 near surface geology the nature of any near surface soils and unconsolidated rocks affects subsidence development with both the thickness and mechanical characteristics of these materials being important 10 hydrogeology the increased groundwater pressure can reduce the effective stress thereby inducing shear on faults 11 elapsed time subsidence does not occur instantaneously but over a period of time harrison 2011 measures that can be implemented to control and minimize subsidence damage fall into the categories of adoption of particular mining methods post mining stabilization architectural and structural design and comprehensive planning in adopting a particular mining technique the principal measures to consider are partial mining changes to the mine layout harmonic mining backfilling and changing the extraction rate for post mining stabilization stabilization of complete mine sites extending over many hectares can be achieved by backfilling as previously outlined grouting or in the case of shallow voids beneath derelict or unused land complete excavation and backfilling concerning architectural and structural considerations where structures are to be built in areas of known or future mining activity designs should be adopted that will tolerate the anticipated ground movements many design techniques are available to produce structures tolerant of subsidence 7 4 7 2 visual impact mining activities specifically surface operations can generate negative visual adverse effects to resources linked to other landscape utilizations such as recreation or tourism potential contributors to visual impacts are roads and highways erosion changes in water color haul roads waste dumps slurry ponds abandoned mining installations fig 7 2 garbage and refuse dumps open pits and deforestation regarding color changes in areas where the color of the rock matches with the natural color of the terrain visual impacts will be less than with sharp color contrasts the impact on landscape by surface mining depends on various factors location size extracted volume and mining methods can influence the impact of mining activities on the visual appearance of the land haney g 2010 restored lands must conform to the visual features of the surrounding landscape the reclamation planning should consider the vicinity to public viewpoints and the visual effect within the context of the viewing distance alleviation methods can incorporate specific location of screening materials including trees and utilization of adequate types of plants in the reclamation stage as well as changes in the location of ancillary installations and access roads in this sense visual absorption capability is described using three physical factors slope vegetation including landscape texture and geology landform dissection visual absorption capability classifies the relative ab

ility of a landscape to accept human alterations without a loss of landscape character or scenic quality a typical example of visual impact is that produced from mine waste dumps and leach pads this is because this adverse effect is a major concern for mines located in the proximity of populated areas or where the facilities are clearly visible from roads and highways landscape alteration can generate an adverse opinion among potential observers and compromise the possible development of the surrounding territory in fact the evaluation of landscape and visual impact often is based more on the subjective perception of the observers which includes cultural and social issues individual opinions aesthetic tastes and visual comprehension and less on the real features of the visible alteration nicholson 1995 for instance las m dulas roman mine fig 1 7 was one of the most important visual impacts of mining two millennium ago and at present unesco includes las m dulas cultural landscape in the list of the world heritage sites however several aspects of landscape modification require to be objectively assessed to estimate the magnitude of change and offer an objective evaluation of the adverse effects originated by pre existing mines or to be generated by new mining operations involving surface excavation landscaping can be undertaken about mineral workings to reduce their visual impact for instance a mine can be screened from view to some extent by the construction of embankments around it that are subsequently planted with grass and trees bell and donnelly 2006 to prevent visual impact a visual resource management vrm should be carried out it was originally created by the bureau of land management us department of interior and the main goal is to manage public land in a manner that protects the scenic values of the lands thus vrm includes inventorying scenic values and determining management aims for those values through the management planning procedure and then assessing suggested activities to establish whether they conform to the management purposes the vrm system is split in two parts the first step is the identification of visual values to determine the appropriate level of management this step called vrm inventory has three components scenic quality evaluation sensitivity analysis and distance zone measures the second part of the vrm system is the analysis stage it includes establishing whether the potential visual adverse effects from suggested surface disturbing activities will meet the management goals defined for the area or whether design adjustments will be requested 7 4 7 3 fire and explosions fires and explosions have the potential to kill people in addition to causing an environmental impact presence of methane is probably the most characteristic source for this issue although flammable and combustible liquids are often stored underground in most mines and pose a special fire hazard wor

ksafe new zealand 2016 the content of methane is specific to underground mines where operations are focused on the exploration or extraction of coal or metalliferous mines and tunnels where methane is present at levels greater than 0 25 for this reason it is essential to develop fire and explosion risk assessments and to identify the measures required to prevent manage and mitigate those risks 7 4 8 revegetation reclamation management must consider soil structure and fertility microbe populations top soil developing and nutrient cycling with the objective to convert the ecosystem as closely as possible to its early conditions sheoran et al 2010 thus establishing vegetation is essential in reclaiming mined lands fig 7 24 the establishment of vegetation can reduce erosion significantly increase evapotranspiration and reduce the amount of water that infiltrates the underlying waste material direct revegetation may allow many of the benefits of a store and release cover to be realized without the need to import large volumes of cover material borden 2011 for instance revegetation of tailings impoundments can be particularly important to prevent dust generation from inactive tailings surfaces as they dry out in this sense some waste surfaces may be directly revegetated after minor physical or chemical modification such as ripping to reduce compaction addition of alkaline materials to increase the ph to near neutral or the addition of organic matter thus revegetation tests for mineral wastes may progress from nutrient analyses and grain size distribution to greenhouse trials and to field revegetation test plots and plant tissue sampling to determine metals uptake borden 2011 fig 7 24 figure 24 revegetated waste rock areas image courtesy of eldorado gold corporation full size image revegetation fosters soil development generates aesthetically landscapes and facilitates post mining land use thus revegetation is the most broadly admitted and helpful manner of restoration of mine works with the objectives to decrease erosion and protect soils against degradation the revegetation must be established with the plants elected in accordance with their capability to subsist and regenerate in the particular environment and on their capability to stabilize the soil framework in this sense numerous factors must be taken into account in an efficient mined land revegetation procedure such as soil features time of seeding species seeded and soil amendment application rates revegetation in a zone impacted by mining works once the final landform has been developed and an adequate growing medium generated includes five main steps a mine soil selection and placement procedures b species selection c planting d seed collection and purchase and e seedbed preparation in general the optimum moment to establish vegetation is defined by the seasonal pattern and reliability of rainfall all the previo

us works must be finished prior the time when seeds are most likely to experience the conditions they need to germinate minerals council of australia 1998 a plan for revegetation includes but not limited to descriptions of the revegetation schedule species and amounts per square meter of seeds and seedlings to be used methods to be used in planting and seeding mulching techniques and irrigation if appropriate pest and disease control measures if any measures proposed to be used to determine the success of revegetation soil testing plan for evaluation of the topsoil results and handling and reclamation procedures related to revegetation nelson 2011 several immediate revegetation establishment options exist including drill seeding hydroseeding broadcast seeding and transplanting entire live plants or plant cuttings in addition the placement of mulch can increase soil moisture provide a temporary cover to reduce erosion risk moderate soil temperature and increase the likelihood of seed establishment 7 4 8 1 mine soil selection and placement procedures correct revegetation processes of active open pit mines start well early of fertilization and seeding thus the most significant stage in surface mine revegetation takes place where the soil is chosen and located on the land surface with the objective to obtain an optimum plant growth the soil must be elected to offer physical and chemical features proper for the aimed post mining land use fertilization and in some instances liming are significant elements of revegetation processes the most efficient manner to attain a correct combination among soil characteristics species and post mining land use is to choose and place surface soil materials to generate a soil that is beneficial to vegetation congruent with the post mining land use declared in the mining permission election and arrangement of surface spoils will have a crucial impact over vegetation success in post mining land use lime fertilizer and organic component additions can be added to remediate issues of low soil fertility and or moderate acidity 7 4 8 2 species selection frequent issues associated with revegetation defeat are the inadequate election of plant species and their unsuitable mixtures sometimes the chosen species are either not adjusted to the site characteristics or to the suggested land utilization the species for establishment will be selected based on the future land utilization of the zone soil characteristics and weather conditions many rehabilitation processes are directed toward the reestablishment of native species if the main goal is to restore the pre mining conditions then the species must be preset fig 7 25 however a decision must be taken whether to utilize only local origin of the native species or to utilize a broad rank of sources this decision requires to be made on a site by site basis usually depending firstly on the degree of similarity between the

pre and post mining environmental features where the aim is the reestablishing of a diverse and permanent cover of local species the following methods of determining suitable species for the post mining conditions should be followed 1 observe plant species growing naturally on any old disturbed areas near the rehabilitation site so that the effective colonizing species can be identified 2 observe the soil and drainage conditions to which the different local species are adapted and match them with the conditions on the mine site 3 identify plant species that produce sufficient viable seed to harvest economically 4 consider habitat requirements where return of wildlife to the area is a significant element of post mining land use 5 consider planting local legume species as they are often good colonizers and will improve soil fertility minerals council of australia 1998 three main types of plants are used for revegetation of mine sites grasses forbs and trees grasses are the most generally seeded plants in revegetation procedures they have fibrous roots that maintain soil in place to control erosion forbs are commonly utilized in mine revegetation combined with grasses while trees are the final plant type they are applied where forested or wildlife habitat land use is selected after mining where agriculture is the desired land use legumes must always be taken into account for their capability to enhance soil fertility legumes are significant for revegetating mine sites since they transfer the fixed nitrogen to other elements of the plant soil system a population of legumes is crucial to an adequate revegetation mainly on sites where topsoil replacement is not sufficient 7 4 8 3 planting the planting techniques elected will be based on the size and nature of the mine sites and the species to establish direct seeding is potentially a costly effective and reliable technique to establish species that generate sufficient numbers of easily collected viable seed with high germination and seedling survival rates advantages include low cost random distribution of plants and no check on growth rates through planting out disadvantages include higher risk of failure through adverse climate conditions competition from weeds loss of seed by insect predation and low seed germination and survival rates for planting seedlings a reliable supplier of seedlings or the establishment of an on site nursery is obligatory fig 7 26 advantages are the effective utilization of forthcoming seed control over species mixture and location and less limitation on the species considered in the revegetation program disadvantages include higher costs for planting and or nursery operation or purchase of seedlings check in growth rate at planting need to preorder or sow several months previous to anticipated utilization longer planting time needed and seedlings can deteriorate if planting is delayed another option to plant

ing is transplanting fig 7 27 transplanting of trees and ground covers is adequate for certain sites or amenity planting advantages include immediate solution and incorporation of species not amenable to other means of propagation main disadvantage is high risk of expensive defeats where individual mature trees are needed for the rehabilitation process transplanting should be ended while suitable earthmoving and lifting equipment is on site minerals council of australia 1998 in some cases the most usual method to seed and apply amendments is using a hydroseeder fertilizer lime mulch fig 7 28 and seed are commonly mixed with water in the hydroseeder tank 7 4 8 4 seed collection and purchase a consistent supply of adequate seed is crucial for the success of revegetation seed can require to be obtained from different zones with the aim to match site characteristics since there are many issues inherent in collecting native seeds seed of several species needs pre sowing treatment thus germination of most native legumes and a number of other species is improved by heat treatment most companies utilize seed mixtures including at least two or three perennial grasses two or three legumes and either a warm season annual or a cool season annual for quick cover thus a broad variety of species is suitable for utilization in mine sites rehabilitation 7 4 8 5 seedbed preparation methods selected for the preparation of the seedbed will be based on topography of the site the required land use the extent of soil amelioration and fertilizer utilization and the sowing or planting method suggested the objective in creating a seedbed is to place the seed in an adequate location for germination for this purpose points to consider include 1 prevent compaction crusting and subsequent erosion by avoiding disturbance to soils when wet and sticky or dry and powdery 2 timing of seedbed preparation and sowing is often critical for successful establishment of vegetation 3 where the topsoil contains significant quantities of seed of desirable species care must be taken not to disturb the soil after these seeds have started to germinate as this will cause a substantial reduction in plant establishment 4 where hand planting of seeds or seedlings is proposed site preparation can best be limited to deep ripping minerals council of australia 1998 7 4 8 6 biosolids biosolids are the dark organic and nutrient rich materials produced as byproduct of current wastewater treatment practices epa 2001 an increasing option to traditional waste disposal is the land application of biosolids since they include many nutrients and metals necessary for plant life biosolids are capable to serve as fertilizers and as a mine reclamation alternative thus biosolids have been utilized successfully at mine sites to establish vegetation not only do the organic matter and nutrients in the biosolids decrease the availability of toxic

components commonly encountered in disturbed mine soils they also build a healthy soil layer where little soil has been left they can also be applied for treating acid mine drainage from abandoned mines biosolids are able to efficiently establish a vegetative cover on contaminated lands and limit the movement of metals through erosion leaching and wind depending on the amendments added biosolids can serve many purposes including ph control metal control and fertilization moreover their adaptability enables them to conform to the specific features of any reclamation site 7 5 potential social impacts a community is usually a diverse group of people with some common bonds diversity can come in the form of gender ethnicity religion race age economic or social status wealth education language class or caste as a result individuals of any community are likely to hold diverse perceptions about a mining operation and its activities as well as most other subjects individuals within a community will have different and sometimes overlapping associations with the mine as neighbors employees suppliers and so on it is not uncommon for disagreement and sometimes conflict to develop between different sections of a community in relation to mining operations evans and kemp 2011 more recently the term stakeholder has become a common term that is related to but distinct from community a common definition of stakeholders is those who have concern in a specific choice either as individuals or representatives of a group this covers people who influence a decision or can influence it as well as those affected by it mcmpr 2005 thus this term can include local community members ngos governments shareholders and employees the social impacts of mining projects have received increasing attention in recent years although it has been commented that mining can be a crucial economic impeller for developing countries because it can facilitate industrialization along with the promises of wealth and jobs mining can also be a source of social discontent in fact the social cost of mining interacts with other cultural and environmental issues that call for concerted efforts in addressing them thus unmitigated negative social impacts have the potential to result in negative publicity incremented litigation processes and reputational damage or to delay prevent or close down mining in existing and prospective areas because of community concerns in this sense it is also interesting to introduce the concept of social risk a social risk is the potential for an existing or planned project to have an impact on individuals or groups or conversely to be impacted by them like impacts social risks are both positive and negative because of the potential for mining to generate social and economic opportunities such as economic and community development and employment franks 2011 many factors can have a significant impact on t

he interactions and relationships between mining operations and communities including various social and political aspects as well as the stage of the mining life cycle involved mining is a truly global activity involving many different types of organizations and communities in settings that range from arid mountains in parts of the andes or remote areas within the arctic circle to established agricultural regions in developed countries and to tropical rainforest settings in developing economies in asia evans and kemp 2011 in this sense political and legal frameworks within a country will have a significant impact on the scale and nature of the mining industry and can also often be the subject of intense community focus government capacity to regulate the minerals industry and manage the benefits of mining for the local communities has been identified as a crucial aspect by recent studies and has been the subject of recent world bank projects in several developing countries in the nineteenth century and most of the twentieth century all involved entities such as governments and mining companies paid little interest to the adverse impact of mining on indigenous people consequently it has become almost impossible for different indigenous communities to commit successfully with contemporary issues that impact on their communities such as resource development propositions commonwealth of australia 2007c based on the above the social impacts of mining activities and projects have received increasing attention in recent years a social impact is considered as something that is experienced or felt real or perceived by an individual social group or economic unit social impacts are the effect of an action or lack of action and can be both positive and negative franks 2011 obviously social impacts can vary in type and intensity and over space and time moreover many times an environmental impact induces a social impact because mining activities can originate changes to community amenities health or accessibility and quality of water and land though it has been argued that mining can be a vital economic propellant for most countries especially the developing ones sometimes it can also be a source of social discontent in fact the social cost of mining interacts with other cultural and environmental issues that call for concerted efforts in addressing them if communities think that they are being unjustly treated or improperly compensated mining projects can originate social tension and violent conflict elaw 2010 communities feel especially vulnerable where links with different sectors of the society are weak or where environmental impacts of mining affect the subsistence and livelihood of local people thus the main impacts of mining projects on social values can include a human displacement and resettlement and migration b lost access to clean water c impacts on livelihoods and public health and d im

pacts to cultural and aesthetic resources elaw 2010 however it could be stated that well managed mineral projects can deliver abroad range of long and short term profits thus many countries have benefited from foreign exchange earnings incorporation of new technologies enhanced investment opportunities construction of infrastructure and education of mine workers and their families anderson 1997 moreover in some cases mine works form the most significant economic resource in this sense the closure of mine can have a strong unfavorable socioeconomic impact the social issues originated by the closure of a mine can be partially mitigated through the retraining of the workers to newer employment possibilities and newer companies aswathanarayana 2005 in spite of the social impacts and concerns literature reveals that efforts at mitigating the impacts of mining have only focused on the environmental impacts and have been wrongly assumed that dealing with the environmental impacts alone would inevitably reduce the social impacts the fact that policy initiative responses are usually geared toward environmental impact assessment implies that social impacts are necessarily not considered opoku ware 2010 thus social impacts are commonly mentioned exclusively in the context of environmental impact studies alluding to impacts that affect communities causing changes in their welfare many companies have concentrated much effort on employment especially for indigenous people and have created programs to support them in their shift from welfare to work jantunen and kauppila 2015 gender is obviously an essential aspect to understand the concept of community mining is usually a male dominated industry but women play significant roles in communities as workers as family members and as individuals and are generally very active forming groups in the community in some situations special effort can be needed to ensure that women s perspectives are sought and that women are proactively included in community engagement and development programs because women are deprived of the access to the benefits of mining developments especially money and employment commonwealth of australia 2006b 7 6 environmental impact assessment eia including the environment into development planning is the most essential tool in accomplishing sustainable development because of the increased concern over the impact of human activity on the environment most countries have adopted legislation requiring that the potential effects of new projects should be assessed consequently environmental protection and economic development must be carried out in an integrated way for this objective the environmental impact assessment eia process is essential to provide an anticipatory and foreseeing procedure for environmental management and protection in any development eia is a complex study that must be developed and approved by the government authoritie

s where industrial operations are permitted in other words the process of establishing potential environmental effects of a proposed project is known as environmental impact assessment and it must enable the best environmental option to be determined and adequate mitigation to be involved nowadays environmental impact assessment and utilizing the required measures for industrial and mining projects are crucial to prevent and control environmental problems the environmental impact assessment procedure is an interdisciplinary and multistage process to assure that environmental characteristics are taken into account in decisions related to projects that can affect the environment in a simple manner the eia process assists to detect the potential environmental effects of a suggested action and how those impacts can be alleviated thus the principal aim of the eia procedure is to inform decision makers and the public of the environmental results of implementing a suggested project the eia process also helps as a decisive procedural role in the global decision making procedure by fostering transparency and public involvement it is important to bear in mind that the eia procedure does not guarantee that a project will be changed or rejected if the process shows that there will be intense environmental footprints in other words the eia process assures a documented decision but not indispensably an environmentally beneficial resolution elaw 2010 at the international level lending banks and bilateral aid agencies have eia processes that implement to borrowing and recipient countries ogola 2007 7 6 1 origin of eia before the first world war quick industrialization in developed countries generated a rapid decrease of natural resources this process maintained to the period after the second world war originating important issues related to pollution quality of life and environmental stress in early 1960s investors notice that the projects they were developing were affecting the environment including people for this reason pressure groups constituted with the objective of getting a tool that can be utilized to protect the environment consequently several developed countries such as australia japan sweden or the usa decided to respond to these problems and established different environmental protection laws for instance sweden published the environmental protection act in 1969 australia the same document in 1974 and the usa developed in 1969 the national environmental policy in those years these documents were the first documented as official tools to be utilized to safeguard the environment regarding these documents complications can take place where there is overlapping among regulation at national regional and local level this can be the case in large countries such as the usa or to member states of the european community furthermore industries working on a global scale may be subjected to a great variety of

eia requirements specific to each country of operation however although eia legislation changes in complexity from one country to the next there is a clear underlying theme potential impacts of certain projects must be assessed and documented during the planning stage likewise the united nations conference on the environment in stockholm in 1972 and further conferences formalized eia nowadays all developed countries and many developing countries have environmental laws to restrict the environmental impacts generated by the industry principle 17 of rio declaration on environment and development in 1992 claim for utilizing eia as a decision making component to be applied in evaluating whether suggested activities are likely to have important adverse effects on the environment thus eia is carried out within the legal and or institutional frameworks defined by countries and international agencies ogola 2007 7 6 2 eia phases the early stage of an eia is termed the initial environmental examination iee and the second is the environmental impact studies eis or merely detailed eia iee is developed to establish whether possible unfavorable environmental effects are important or whether mitigation measurements can be adopted to decrease or even remove the adverse results the iee includes a short statement of main environmental problems obtained using forthcoming information and it is utilized in the first stage of project planning the iee also decides if further in depth studies are required where an iee allows offering a final solution to environmental issues of a project an eia is not needed eis or detailed eia is a process utilized to study the environmental effects both positive and negative of a proposed project and to assure that these consequences are considered in project design consequently the eis is based on predictions the adverse effects can include all significant items of the natural social economic and human environment the study needs a multidisciplinary focus and must be carried out very early at the feasibility stage of a project in other words a project should be assessed for its environmental feasibility thus eis should be established an integral part of the project planning procedure finally the analyses of alternatives are carried out to define the preferred or most environmentally sound financially viable and benevolent possibility for accomplishing project goals the world bank directives request systematic comparison of suggested investment designs for each alternative the environmental cost is estimated as far as possible and economic data enclosed where feasible and the selected alternative stated the analysis of alternatives must always incorporate the so called no project alternative 7 6 3 impact analysis and prediction predicting the extent of impacts and estimating their significance are essential in environmental impact assessment processes prediction should be based

on the available environmental baseline of the project area being these predictions described in quantitative or qualitative manner according to ogola 2007 the considerations in impact prediction must include 1 magnitude of impact this is defined by the severity of each potential impact and indicates whether the impact is irreversible or reversible and estimated potential rate of recovery the magnitude of an impact cannot be considered high if a major adverse impact can be mitigated 2 extent of impact the spatial extent or the zone of influence of the impact should always be determined an impact can be site specific or limited to the project area 3 duration of impact environmental impacts have a temporal dimension and need to be considered in an eia an impact that generally lasts for only 3 9 years after project completion can be classified as short term an impact that continues for 10 20 years can be defined as medium term and impacts that last beyond 20 years are considered as long term 4 significance of the impact this refers to the value or amount of the impact once an impact has been predicted its significance must be evaluated using an appropriate choice of criteria 7 6 4 methods for identification of effects and impacts there are three main methods for assessing environmental impacts checklists flow diagrams and matrices sorensen and moss 1973 checklists are complete registers of environmental effects and impact gauges established to encourage the analyst to think widely about potential consequences of contemplated actions however this strength can also be a weakness because it can lead the analyst to ignore factors that are not on the lists in any form checklists are included in almost all eia methods in some cases flow diagrams are utilized to look for action effect impact relationships they allow the technician to visualize the connecting between action and impact this method is most suitable to single project assessments not being recommended for large regional actions regarding matrix method it is probably the most used in the eia box 7 5 matrix method in the eia the matrix method in environmental impact assessment studies can be very helpful due to its simplicity and understandability of its algorithm 7 6 box 7 5 7 6 matrix method in the eia the matrix method was initially developed by dr luna leopold and others of the us geological survey leopold et al 1971 in response to the environmental policy act of 1969 as gillette previously stated gillette 1971 the law s instructions for preparing an impact report apparently are not specific enough to insure that an agency will fully or even usefully examine the environmental effects of the projects it plans this method consists of a matrix that is primarily a check list designed to show possible interactions between development activities and a set of environmental characteristics combining these lists as horizontal and vert

ical axes for a matrix allows the identification of cause effect relationships between specific activities and impacts this matrix has 1 on the horizontal axis the actions that cause environmental impact and 2 on the vertical axis the existing environmental conditions that can be affected by those actions this provides a format for comprehensive review of the interactions between proposed anthropogenic actions and environmental factors characteristics and conditions the entries in the cell of the matrix can be either qualitative estimates or quantitative estimates of these cause effect relationships the latter are in many cases combined into a weighted scheme leading to a total impact score the original leopold system was an open cell matrix containing 100 project actions along the horizontal axis and 88 environmental characteristics and conditions along the vertical axis this provides a total of 8800 interactions however in practice only a few of the interactions would be likely to involve impacts of such magnitude and importance to warrant detailed treatment matrix methods identify interactions between various project actions and environmental parameters and components they incorporate a list of project activities with a checklist of environmental components that might be affected by these activities they should preferably cover both the construction and the operation phases of the project because sometimes the former causes greater impacts than the latter simple matrices are useful 1 early in eia processes for scoping the assessment 2 for identifying areas that require further research and 3 for identifying interactions between project activities and specific environmental components matrix method is probably the most used in the identification of effects and impacts however it also has their disadvantages since it does not explicitly represent spatial or temporal considerations and does not adequately address synergistic impacts figure 7 29 shows an example of an environmental impact matrix the eia is the accepted method for evaluating proposed mining projects to obtain regulatory approval and to help companies plan for responsible development from its early beginnings to its development over the past three or four decades the eia has become increasingly exacting paralleling the development and expansion of international and national standards generally accompanied by environmental and social management plans the eia has undeniably become the essential regulatory document required of new mines by governments worldwide mitchell 2012 thus before any mining project can be carried out it must undergo an environmental assessment as legislated by local or national governments in this sense each jurisdiction has different regulations governing environmental review and some are more stringent than others stevens 2010 initially an eia was only requested in highly regulated circumstances no

wadays it is impossible to find a major mining project anywhere in the world that is not requested either by legislation or corporate standards to undertake an eia in general an eia for a mining project must include a assessment of the current state of the environment b definitions of various project alternatives assessments of their environmental impacts and a comprehensive picture of the impacts of the project and its implementation alternatives presented together with assessments of the scale and significance of such impacts c plans for the mitigation of detrimental impacts and d the publication of an accurate and coherent eia report jantunen and kauppila 2015 eia of mining projects request an approach of the entire life cycle of a mine from exploration to mine closure and reclamation mining companies have realized that this is the most cost effective method to planning and managing a mine and particularly to managing environmental effects weaver and caldwell 1999 in summary eia can help to reduce costs and unscheduled project delays and minimize future economic and environmental liabilities as aforementioned a credible approach to eia by the proponent company can serve to support the reputation of both the company and the mining industry generally as participants in planning for the sustainable development of the world s resources in this sense key aspects of the eia procedure of mining projects must include a broad participation b the public availability of documents prepared during the eia procedure eia program eia report and the statements and opinions of the competent authority and other parties c review of the various project alternatives d broad definition of the environmental impacts of the project and e assessment of the environmental impacts that will occur during the various stages of the project planning construction and commissioning operation and closure jantunen and kauppila 2015 in all the eia procedure consultations are an essential component of the environmental revision process consultations enable experts government communities and indigenous people a possibility to discuss the adverse effects of the mining project occurring at different phases in the review process in this sense mining companies that adhere to the principles of sustainable development commonly include consultations since the early prospection stage of the mineral deposit as a result the company will likely have addressed any significant concern with the project before it officially begins the review process depending on the eia method liability for generating a mining eia will be allocated to one of the following the government agency or the project proponent for proponents a correctly coordinated eia of a suggested mining project can help substantially to efficient planning if eia laws permit either party can opt to recruit a consultant to carry out the eia or handle certain p

arts of the eia procedure in this sense some eia laws accept conflict of interest generated where a mining company or other project proponent recruits an external consultant to draft an eia utilizing a consultant carries the risk that the paper will be influenced in favor of developing the mining project for this reason some laws request consultants to be registered with the government and or a professionally accredited organization in eia preparation in some cases a consultant can be requested to file a statement disclosing any financial or other interest in the result of the project elaw 2010 7 6 5 1 stages of the eia process eia must be a procedure that proceeds throughout the life cycle of a mining project with results that become ever more accurate figure 7 30 shows the eia process in connection to the commented life cycle of a mine jantunen and kauppila 2015 pre feasibility reports usually offer an adequate basis for carrying out an eia because they classically approach to the geology of the property types of ore deposits resource estimations mining and mineral processing techniques management of mining wastes requirement for infrastructure water and energy consumption and labor and transportation costs at this phase estimates of these factors cannot be awaited to be especially accurate margins of error can range between 20 and 30 this is because the information about the project is still clearly imprecise to generate a suitable eia the planning of the project must be so advanced that its adverse effects can be evaluated accurately and reliably enough for instance it is essential to have precise knowledge of the technical solutions that will be utilized in the project to allow accurate quantitative and qualitative assessment of emissions however the eia process cannot be left too late because it must be finished before a mining project can obtain the necessary permits it is a sound practice to start the permit procedure for a project only after the eia process has been finished thereafter the eia document and the qualified authority s statement on the report must be enclosed to the permit applications for the mining project thus the eia process is commonly formed by a group of procedural stages culminating in a written impact assessment document that will report the decision maker whether to approve or reject a proposed mining project elaw 2010 the first stage includes the identification and definition of the project or activity although this stage can be comparatively easy definition of a project for the purpose of an eia can be very difficult and even controversial if a mining project is large and has several phases or multiple sites must be covered the aim of this phase is to define the project with sufficient specificity to accurately establish the area of potential adverse effects and to incorporate activities that are strictly linked with the proposition so that the entire scope of e

nvironmental impacts is assessed in this step the screening process establishes whether a certain project warrants preparation of an eia in some instances especially if the potential impacts of a project are not understood a previous environmental evaluation will be outlined to establish whether the project warrants an eia the next step scoping commonly involves the interested parties that identify the key environmental problems that should be addressed in an eia this phase offers one of the earliest opportunities for members of the public to learn about a suggested project and to voice their opinions scoping can also show connected activities that can be occurring near a project or identify issues that request to be mitigated or that can originate the project to be canceled in this procedure the terms of reference serve as a roadmap for eia preparation and should ideally embrace the adverse effects that have been identified during the scoping a draft terms of reference can be made forthcoming for public revision and comment public revision at this first phase of the process originates a good opportunity to assure that the eia is adequately framed and will address issues of community concern then a draft eia is developed according to the terms of reference and or the rank of problems identified during the scoping procedure the draft eia can also meet the content requirements of the global eia regulations this phase will ideally take part a broad range of technical specialists to assess baseline conditions forecast the likely adverse effects of the project and establish mitigation measurements regarding baseline studies they identify the present status of the physical social and economic environment before the project starts and technical studies define the features of the project the technical details of the project will be obtained from pre feasibility or feasibility studies that commonly are finished previous to beginning of the environmental assessment process baseline studies generally take several years to complete and in some cases commonly start at the beginning of the exploration stage stevens 2010 the next stage generates a final impact assessment document that tackles the points of view and comments of the parties that revised the draft eia these comments can promote revisions or additions to the report of the draft eia in some instances this final eia will include an appendix synthesizing all of the commentaries received from the public and interested institutions and supply responses to those comments a decision to approve or reject a mining project is commonly based on the information provided for the final eia but in some cases an environmental clearance can be just one stage in the mine permitting procedure once the mine is permitted monitoring procedure is an important tool of project implementation according to elaw 2010 monitoring serves three purposes 1 ensuring that required

mitigation measures are being implemented 2 evaluating whether mitigation measures are working effectively and 3 validating the accuracy of models or projections that were used during the impact assessment process 7 7 social impact assessment sia social impact assessment sia can be defined as the process of managing the social issues of projects to be efficient the management of social issues requires to begin from the moment a project is early planned right through to further closure corporations can carry out sia as part of their liability to address their social impacts and their wish to obtain a social license to operate the origin of this type of study was in the 1970s and the main goal of sia has varied from early concerned about the adverse impacts of a project to being more concerned about how a project can be improved this is with the aim of increasing the profits to communities so that both communities and companies can benefit from the project these studies will have more importance in the near future and its request will continue to increase for several reasons including the incrementing investment in developing countries in this sense a combined action of weak institutions and decreasing land accessibility generates potential for disagreement between companies and communities mainly if the risks are not early defined and mitigation planning is not implemented or not carried out in cooperation with the impacted peoples themselves in addressing the social aspects of sustainable development social impact assessment early emerged as a component within environmental impact assessment eia used to evaluate moderate and invariantly mitigate the impact of planned interventions esteves et al 2012 mahmoudi et al 2013 the impact of projects and policies on the social welfare of communities is clearly a topic of increasing concern which justifies the increased development and practice of sias in the last years e g vanclay and esteves 2011 moreover sia is a common requirement of regulatory approval processes at the project approvals phase for mining and processing stages in many jurisdictions the good practice of sia accepts that social economic and environmental issues are inherently interconnected thus change in any of these fields immediately generates changes in the other domains according to esteves et al 2012 there is consensus on what good sia practice is a it is participatory b it supports affected peoples proponents and regulatory agencies c it increases understanding of change and capacities to respond to change d it seeks to avoid and mitigate negative impacts and to enhance positive benefits across the life cycle of developments and e it emphasizes enhancing the lives of vulnerable and disadvantaged people social impact assessment has been early included within the field of sociology and related sub areas environmental sociology human geography etc but d

ifferent professionals from many disciplines have developed experience in the field it is essential to consider the sia in context with the other parts of the project specifically the environmental impact assessment that must be also submitted with the application for an exploitation license bmp 2009 social impact assessment and management are the responsibility of community relations practitioners at most mining operations however there is a need for mining engineering professionals to be familiar with such perspectives because efficient management needs integration across all aspects of the operation sia and impact management are most effective where carried out in all the life cycle of mining including all of the activities from exploration construction extraction and processing through to post closure as well as also incorporating recycling and waste management the diverse social impacts across the mine life cycle stages and the extraction and resource processing phases require a complete rank of approaches to assessment and management 7 7 1 general overview of sia social impact assessment involves the processes of analyzing monitoring and managing the social consequences both positive and negative of planned interventions policies programs plans projects and any social change processes invoked by those interventions its first goal is to achieve a more sustainable and equitable biophysical and human environment vanclay 2003 contemporary sia arguably began along with eia in the early 1970s in response to the formal requirements of the national environmental policy act nepa 1969 of the usa the first sia document was the publication in 1994 of the guidelines and principles for social impact assessment by the us inter organizational committee a milestone case in the establishment of sia was the inquiry at 1974 by chief justice thomas berger into the suggested mackenzie valley gas pipeline from the beaufort sea to edmonton alberta canada it was the first occasion that social impacts had been formally taken into account in project decision making the sia finally recommended that the project be postponed for at least 10 years to enable sufficient time for land claims to be settled and for new programs to help the native population the findings were at the time unprecedented and marked the start of a huge growth in sia joyce and macfarlane 2002 today many institutions and national governments consider sia as a mandatory activity for project proposals other procedures related to social impact assessment are health impact assessment hia and strategic environmental assessment sea in most eias hia is usually included under sia hia is a wide concept that implies an interest in the safeguarding and improvement of human health regarding sea it is carried out much earlier in the decision making process than eia being thus a key tool for sustainable development sea aims to include environmental

and sustainability aspects into strategic decision making procedures such as the formulation of policies plans and programs 7 7 2 sia for mining projects large scale mining projects can generate different and intense social impacts they can differ significantly based on the duration of the project the position of populated areas related to the project area and the potential mine expansion planning most eia guidelines require social impact analysis this implies that specialists in several fields are involved in planning implementation and monitoring throughout the mining project life in this sense it is essential to take into account the social impacts of mining on the surrounding environment and affected communities and to include social impact assessment into the operational activities of a mine as a management tool the social impact assessment should consider baseline information related to at least the four following areas 1 changes in access to and power over local resources land water 2 changes in the characteristics of a population size composition traditions productive activities 3 divergent perceptions between decision makers the mining company and local people about the distribution of economic benefits and social environmental costs of a large mining operation and 4 land property and use elaw 2010 for instance relocation of a population is a vital social problem to resolve this issue environmental impact assessment must incorporate detailed information about compensation relocation planning and information about consideration to guarantee people similar quality of life 7 7 2 1 phases of a mining social impact assessment a list of sequential steps should be followed in the sia process drawn primarily from the environmental impact assessment eia steps arce gomez et al 2015 thus franks 2011 affirmed that mining social impact assessment can include a number of distinct but iterative phases within an adaptive management process fig 7 31 1 scoping and formulation of alternatives 2 profiling and baseline studies 3 predictive assessment and revision of alternatives 4 management strategies to avoid and mitigate negative social impacts and enhance positive impacts 5 monitoring and reporting and 6 evaluation and review the scoping stage establishes the criteria for the further stages of assessment and management by determining the scale timing and focus of the assessment establishing who is likely to be impacted and detecting the actions that are likely to result in impacts in this stage alternative possibilities must be defined for further studies and a first evaluation of the impacts of these alternatives carried out the output of this phase can be to consider the aim scope scale priority issues and terms of reference for the following phases of assessment and management the second stage includes understanding the communities and stakeholders potential

ly affected by the activity through social and economic research profiling includes studies of the social and economic features of an area at a given point of time in turn baselines are an evaluation of the state of a community before a mining activity occurs thus baseline information must generate a clear description of present social conditions in the area potentially impacted by the project before it is realized regarding predictive assessment and revision of alternatives the outcomes of predictive assessment are generally prioritized by their scale and level of significance they are utilized to offer feedback to stakeholders and project developers with the aim of modifying and revising the project they allow them to make the decision to which suggested project alternative best accomplish the goals of the project while still improving social outcomes and preventing negative impacts different scenarios for the project design might be significant to describe apart from describing the zero alternative where the possible consequences are explained if the mining project is not finally developed the monitoring and reporting stage includes collection analysis and dissemination of information through time as a rule a well defined monitoring plan shall include 1 outline of the monitoring methodologies to be applied to measure progress 2 baseline information on which progress can be measured 3 well defined indicators for each program and identified impacts in the sia the indicators can be quantitative or qualitative and they shall be of scientific quality 4 frequency while baseline information provides a picture of the present situation explicit and verifiable parameters are needed in order to assess the progress made bmp 2009 the final phase evaluation and review evaluates and reviews both assessment and management processes the reconciliation of impacts estimated in the assessment stage with the actual impacts undergone during implementation will contribute to refine and enhance future perspectives a well defined evaluation plan shall include an outline of the evaluation methodologies to be applied and a plan of action for handling the outcome of the evaluations computers are an essential tool to conduct mineral inventory studies and a significant amount of software exists that has been developed specifically thus the use of computers to process geological data as well as to design the mine has become a boom in mineral industry the continued progress over the last 25 years allowed the mining software to run from the simplest to the most complicated options the software is continuously updating to fulfill the needs of the customers and users to carry out mineral inventory studies without the use of these computing facilities is actually a huge mistake since software procedures form part of modern mineral inventory practice being impossible to obtain similar results making calculations by hand most resour

ce calculations carried out in exploration in pre feasibility or feasibility studies or in grade control and scheduling utilize a specific software package that handle 3 d data at the early stages of exploration the main features of the software will be to input borehole information and link this information to the surface features where a resource or reserve is being estimated the capability of the package to model the shape of geological units and calculate volumes and tonnages becomes essential it is essential that the user is very specialized about the subject data input and the possible result expected at the end of the processing mining software is used in a wide variety of applications 1 databases to record geological data coming from diverse sources such as surveys drillholes geochemical analysis geological structures rock mass behavior processing and production costs etc 2 statistical analysis to manipulate and summarize the very large and complex data sets that are typical of exploration and mining operations 3 a wide variety of estimation tools for creating spatially continuous models of geological structures 4 computer aided design cad facilities that are specialized for accurate and efficient modelling of geological structures and mine openings and 5 an array of specialized algorithms that serve as aid for engineering design smith 1999 8 2 types of mining software available software can be classified as public domain and commercial as a rule public domain software is free and incorporate full source code but it does not usually include guarantees or technical support this type of software is commonly forthcoming from universities government organizations textbooks technical literature and diverse user groups accessible through internet on the contrary commercial software although more expensive generally comes with an up to date user s manual and also including a technical support system from the company however the source code is often generally proprietary the software packages are typically integrated that is the different capabilities are available in modules that can be purchased separately obviously the package selected must depend on the finance accessible and the needs of the users at any given moment since there are modules specifically devoted to open pit mining underground mining and so on 8 2 1 inexpensive software inexpensive software includes from freeware or public domain software to software included in a book an example of the first is geoeas tools regarding the software programs included in a book csmine software is delivered with the book entitled open pit mine planning and design third edition 2013 8 2 1 1 geoeas geostatistical environmental assessment software geoeas was developed by the environmental protection agency at 1991 so this system was designed to run under dos and consequently works badly in modern equipment most of them using 6

4 bit architecture however it is possible to run properly the program using emulation software such as doxbox geoeas is probably the most famous public domain geostatistical software in the history being a suite of tools for carrying out two dimensional geostatistical analysis of spatially distributed data geoeas can produce data maps univariate statistics scatter plots linear regression and variogram computation and model fitting fig 8 1 but the main function of the package is the generation of grids and contour maps estimates obtained by interpolation using kriging methods once the drillhole database has been selected geoeas provides a stat1 program for univariate exploratory data analysis it is essential to have a look at the histogram of the data and to maintain it in mind during the different processes since variogram modeling and kriging estimation are very susceptible to the presence of extreme values then the vario program is selected the main goal of vario is to develop a mathematical model of the spatial continuity of a variable variogram adjusting the model to the experimental semivariogram later xvalid control the goodness of fit of the model selected finally krige program carry out 2 d estimation using kriging 8 2 1 2 csmine the main emphasis of the program is on open pit mine planning because the book in which the program is included is mainly devoted to this topic the program is designed to take raw drillhole data through the block modeling process to the generation of the final economic pit limits the major features of the program include 1 graphical displays of drillhole data drillhole plan maps and drillhole section or profile maps 2 compositing of raw drillhole data to regularly spaced samples for processing by the block model 3 block modeling by the inverse distance squared method or kriging it includes graphical presentation of the block model data block plots and contour plots through any bench or section 4 assigning of economic values to the blocks and their graphical presentation and 5 final pit limit generation including geometric pit limits defined by the surface topography and pit slope constraints and economic pit limits defined by a three dimensional floating cone algorithm thus the program is divided into three modules to deal with the three types of data these are a the drillhole mode used to read in and display the raw drillhole data b the composite mode used to regularize the raw drillhole data into composites of equal length and c the block mode used to create and display the block model to assign economic values to the blocks and to generate the final economic pit limits 8 2 2 commercial software there is a number of software packages of this type in the market they can be classified into two main groups 1 software with applications in mining and 2 specific mining software the former are programs with mining applications such as surfer or ro

ckworks although rockworks is more specifically delivered as geological utilities software below are very brief descriptions of an example of each group rockworks and datamine respectively regarding specific mining software there are several packages available in the market table 8 1 many of the companies were founded in the late 1980s but a range of acquisitions in the following decades change dramatically the market for instance three of the most popular softwares in those times such as whittle gemcom and surpac are now property of geovia on the other hand companies such as micromine or maptek remain the same whittle is an exciting example of this acquisitions trend some common characteristics of this type of software are a they offer integrated tools for modeling estimation mine design optimization and scheduling b they are compatible with many third party software applications including gis google earth als coreviewer and various mining applications c they can manage and visualize very large and complex data sets process the information and rapidly generate models d they usually offer multilingual support english spanish french etc e they are commonly organized in modules or separate programs each one specifically devoted to the different parts of the mining process that is exploration database geological and block modeling resource estimation mine design and optimization and scheduling rockworks is a comprehensive software with modeling of spatial and subsurface data as the main tool it was developed by rockware company at the beginning of 1990s and is probably the most important software worldwide for geological utilities the latest version is rockworks 17 rockworks applications include a petroleum well spotting structural and isopach mapping logs and cross sections stratigraphic models and fences production graphs b environmental borehole database for lithologic stratigraphic analytical data point and contour maps logs cross sections plume models c mining drillhole database for lithologic assay geophysical data 2 d and 3 d log diagrams block modeling detailed volume tools d geotechnical borehole database for lithologic geophysical geotechnical data logs sections surface solid models structural tools mining applications can be arranged in three levels borehole database tools mapping tools and other tools such as block modeling and volume calculations rockworks is organized in two main data windows borehole manager and utilities the borehole manager includes a data window and a suite of menus to enter and work with borehole data in this tool most of the subsurface modeling and visualization in rockworks e g 2 d and 3 d logs cross sections solid and stratigraphic models among others is carried out the utilities data window is a simpler row and column type of data window with its proper group of menus it is possible to generate

diverse types of maps charts and diagrams 8 3 1 borehole manager borehole data include location orientation lithology stratigraphy colors fractures water levels symbols patterns bitmaps vectors construction production and data and text information for each borehole for instance orientation information in each borehole includes depth azimuth and inclination in downhole survey points once the information for all the boreholes is located at the proper item many options are present to visualize one or several boreholes from single borehole to sections including several boreholes and from 2 d to 3 d visualization figure 8 2 is an example of borehole locations with ground surface contours and fig 8 3 is an example of 3 d visualization of the borehole lithology data another interesting option in borehole manager is the lithology model option this program creates a 3 dimensional solid or block model representing interpolated lithology types and displays the model as a 3 d voxel diagram fig 8 4 the lithologies will be represented in the model using the numeric g values declared in the lithology types table 3 d logs can be attached the image when needed the completed voxel diagram will be showed in a rockplot 3 d window where it is possible to handle the display filtering specific values and show volumes among many others regarding the volume of each lithology the volumetrics option reads an existing lithologic solid model and creates a tabular report by computing the total volume and or mass for each lithotype based on the relative depth elevation the estimations obtained are presented in a row and column datasheet for each type of data included in the borehole database many options are available for example plan map and histogram plan map creates a 2 d map displaying the interpolated values where the model intersects a horizontal plane the completed map is showed in rockplot 2 d histogram tool is used to read a single column of data from all boreholes and compute the frequency or percentage of the measures for that variable that is included in each grouping or cell previously defined by the user the values then are displayed using a bar histogram plot 8 3 2 utilities this module or group of programs includes many interesting applications in mining in summary four main menus are present map grid solid and volumetrics the map menu reads spatial data from the datasheet editor and generates a variety of different maps points contours polygons 3 d points etc the grid menu manipulates grid models statistics filters editing imports directional analysis etc the solid menu creates manipulates and analyzes solid models finally the volumetrics menu computes volumes creates extraction surfaces creates gt reports etc in the map menu for example the grid based map program reads xyz data from the datasheet interpolates a grid model and creates a 2 d map with symbols labels grid

based line color contours triangle network background image and or border annotation 3 d surfaces are also created in the grid menu the polygon filter is utilized to set the grid nodes inside or outside a defined polygon to either a level specified by the user or to the values established in another grid model a classical application of this tool is to set zero to all the values out of the polygon for instance if the input grid model depicts mineralization reserves and the polygon means a lease boundary the grid statistics will compute mineralization reserves only within the lease boundary in addition grid math carries out arithmetical operations with the grid node z values in two existing grid files this is very useful to estimate the amount of raw material mined in a period e g 1 week 1 month or 1 year considering a grid model for the first day of the month and a grid model for the last day of the month the subtracted grid will offer the amount cited in each case grid statistics report option shows all the values of the grid model including model volume which represents the volume of the raw material included in the model in the solid menu the model program generates a solid model from x y z and g data in the utilities datasheet and creates a 3 d isosurface diagram or all voxel diagram representing the solid model rockworks offers several different methods to interpolate the solid model and many different display settings the values to be modeled g values can represent geochemical concentrations e g grades in a mineral deposit geophysical measurements geotechnical parameters etc figure 8 6 is an example of this type of model representing lead concentrations displayed as an isosurface diagram with boreholes in the volumetrics menu two programs are highlighted 2 d grid model and extract solid the grid model is utilized for estimating formation volume from a column of thickness values in the datasheet and including different filtering parameters the computations are grid based being the gridding algorithm e g kriging closest point or inverse distance weighting selected by the user some of the advanced filtering options contain thickness stripping ratio up to five quantitative data column range constraints polygon areas and distance in addition it is possible to invoke a polygon clipping filter so that only those thickness nodes within a user entered polygon area are included in the computations the output report can even list proven probable and inferred reserves based on user declaration of distance confidences the grid based volume calculator offers several types of output a a grid file containing the numeric model for the final filtered grid of formation thickness values or mass values if requested b a 2 or 3 d map that illustrates the final thickness or mass grid and or c a report that lists in detail the intermediate and final volume computations with

weight computations if requested regarding the extract solid option this program consider an existing solid model e g lithology type and establishes the volume of a pit that would be needed to extract the parts of previous solid model that fall within a defined range e g a selected lithotype the output is a report that includes the pit the volumes and the stripping ratios a 2 d diagram showing the pit elevations and or a 3 d diagram illustrating the filtered solid and the pit elevations fig 8 7 obviously the surface grid model must have the same dimensions as the x and y dimensions of the input solid model maximum overall slope and bench heights can also be defined datamine provides a range of integrated mining solutions for the all the processes involved in mining development it incorporates software tools for exploration fieldwork resource modeling as well as all levels of mine planning strategic optimization detailed design and short term decision making thus the different programs can be grouped into four main categories geological data management software resource reserve modeling software open pit planning software and underground planning software four of these programs dhlogger datamine studio datamine studio op and npv scheduler are briefly commented below exploration data forms the fundamental underlying basis for resource models and mining resource reserve evaluations being critical for mining companies to carry out a protection process of the investment with modern systems that control all the processes and safely store the data in this sense datamine provides a range of integrated tools for data capture analysis storage and reporting of geological geotechnical and geochemical information this software category includes programs such as dhlogger sample station mine mapper fusion report manager laboratory information management system and core shed management datamine s resource modeling system delivers geological models for all types of mines across the full range of deposit types it includes programs such as studio em studio rm strat3d and ore controller regarding the third group datamine provides a full range of open pit planning applications from strategic long term optimization pit design reserve generation and operational equipment scheduling incorporating programs such as npv scheduler summit strategic open pit planning and studio op fig 8 8 finally datamine underground mining software helps to design plan and schedule all aspects of the underground mining this category includes programs such as mineable shape optimiser summit underground strategic optimisation studio 5d planner enhanced production scheduler aegis and ventsim the main purpose of fusion software is to enable clients to collect validate manage and deliver geological data for the project improve the flow of geological data throughout an organization and minimize the time re

quired to work with the data at all levels their capabilities include a data collection e g data import from many external data sources like txt csv ms access data validation ensuring that the data is correct standardized pick lists or automatic validation of laboratory results b data management e g captured data transferred to a central location and c data delivery e g share data with other users utilizing the fusion applications or share data with external applications using custom export routines regarding data collection and validation applications dhlogger software captures and manages drillhole data the sample station module captures and manages point sample data the minemapper3d option captures and manages 2 d 3 d mapping data and century lims captures and manages mine lab data 8 4 1 1 dhlogger the main objectives of dhlogger are the following a to complete drillhole data capture including collar geological and technical details samples and related qa qc materials b to import analytical results using the lab import utility c to import external geology data using the drill hole import utility d to convert grid coordinates from one system to another e to calculate sample composite intervals and f to manage dispatch of samples and drill costs in dhlogger the data is entered into dhlogger through the use of three types of data entry screens collar details and samples the details view of the drillhole window is used to log major and minor interval data for the hole minor intervals must be associated to major intervals and typically describe small or less significant core properties such as alteration or minor lithology all texture structure alteration and mineralization records are generally linked to specific major and minor intervals all rqd data magnetic susceptibility direction coordinates and wedge records are generally linked to the hole if there are gaps in core a no core available rock type or something similar must be created and used to represent such intervals in the details view the samples interface contains all of the sample and assay data associated with a particular hole it is possible to import drillhole data from a comma or tab delimited format into dhlogger in a two step process defining which tables data will be imported into and defining which columns data will be imported into on the other hand the worksheet of the samples interface is used to calculate and save averages from a series of hole samples regarding data management the fusion administrator option administers the fusion data model manages users and defines validation constraints the fusion client option transfers data between databases and synchronizes administration changes and the fusion scheduler option transfers data from a remote site to a central location on a scheduled basis for data delivery querybuilder queries the database exports results manages qa qc charts a

nd creates custom reports and crystal report viewer displays prints and saves custom reports finally report manager creates automate qa qc reporting 8 4 2 studio rm creating a geological and resource model is an iterative process with greater understanding of the geology and grade distribution being achieved as the study proceeds and more data becomes available the process of creating a 3 d geological ore body model typically makes use of the topography contours drillholes structural data e g fault surface ore body string model section strings top or bottom contact contours ore body wireframe model and waste and ore block models the addition of user defined alpha or numeric attributes e g zone mineralization zone number or density rock density and the use of data filters views and formatting symbols and linestyles facilitate the geological modeling process and enable the generation of professional outputs such as summary reports plots and 3 d views in general the geological modeling process using a mining software includes the following steps a importing drillhole data b importing topography c geological string modeling d geological wireframe modeling and e geological block modeling 8 4 2 1 importing drillhole data drillhole data is used as a basis for creating geological models the drillhole tables typically consist of collars downhole surveys and downhole samples tables the minimum field requirements for the tables are as follows a collars bhid drillhole identifier xcollar collar x coordinate ycollar collar y coordinate and zcollar collar elevation b surveys bhid drillhole identifier at downhole depth brg bearing in degrees and dip dip in degrees c assays bhid drillhole identifier from downhole interval start depth to downhole interval end depth assay1 first assay field numeric values units as defined by the user for example in g t or percentage and assay2 second assay field many assay fields are permitted depending of the mining software d depth data tables bhid drillhole identifier at downhole depth and attribute1 alpha or numeric attribute such as geological structural measurement or downhole geophysical survey parameter e interval data tables bhid drillhole identifier from collar x coordinate to collar y coordinate and attribute1 alpha or numeric attribute such as interpreted mineralization zone flag code or rock density figure 8 9 is an example of this type of drillhole data the drillhole data can be imported from other formats such as ascii space delimited format or microsoft excel worksheet format to generate the mining software datamine format once the drillhole data is imported a standard procedure for checking and correcting possible errors in the data is carried out immediately it would be compared the listed errors against the relevant records in the source files e g database text files or spreadsheet

and correct data entries where required with the data imported in the datamine table editor different processes can be performed such as to locate the positions of the drillhole collars to show the drillholes in the 3 d window to define sections fig 8 10 and much more another possibility is to obtain the summary statistics of different data including minimum mean and maximum mineral grade values for instance to investigate the parametric summary statistics and to check for outliers compositing down drillholes is a process that will be essential in successive steps the composited drillholes will be a composited by rock type or domain by setting a very large interval to generate individual rock type composites to be used for rock type or domain boundary modeling and or b composited by a fixed interval such as minimum mining width or block size for geostatistical analysis 8 4 2 2 importing topography although the topography can be created using a number of points the most common way to obtain the topography of the selected area is to import the topography contours data from an autocad file and generate the datamine format strings file the cad drawing file commonly has the data of polylines which represent topography contours and a bounding perimeter e g contour interval 10 m elevation range 60 250 m x coordinate range 5610 6780 m and y coordinate range 4600 5779 m at this point an integrated topography drillholes view can be displayed in the 3 d window the next step in the process is to create the basic framework for a geological ore body string model it consists of sets of vertical section strings that are guided by the mineralized zones displayed in the drillhole data the strings will then be saved to a datamine file the section perimeters closed strings are used to model the ore body where a drillhole data is organized in sections b ore bodies have complex geometries e g irregular shapes and or c needing to generate closed wireframe volumes the interpretation of mineralization zones and the creation of geological string models for ore bodies can be done using a variety of string modeling methods such as vertical horizontal or inclined section perimeters closed strings and contour strings e g separate top and bottom ore zone contact contours surface topography as a rule the perimeter is digitized in a clockwise direction the start point is the extrapolated top of the upper zone position points are digitized on the top top contact or bottom bottom contact of the relevant drillhole segments by pointing or snapping to segment ends the string points are labeled with the digitizing sequence and the string will be closed to create a closed string perimeter the same process is carried out in the different drillhole sections to create a string model therefore the string model consists of sets of section strings that have been digitized for example in vertical n s planes and spa

ced 25 m apart the translation distances of the sections along a specific coordinate axis can be either positive or negative that is translation in the direction of increasing coordinate values e g 25 or translation in the direction of decreasing coordinate values e g 25 figure 8 12 shows an image of the extended string model relative to the drillhole and topography surface contour data then tag strings are added to the existing geological ore body strings model they are added in order to control the exact placement of wireframe edges and overcome the problem of twisted wireframes associated with complex geometries the strings will link the northern and southern ends of the upper and lower mineralized zone strings between adjacent n s sections that are spaced 25 m apart finally the different string models topography and ore body are combined into a single object it is useful for simplifying object management where a large number of string model objects are used and as a means of simplifying a data set for presentation purposes 8 4 2 4 geological wireframe modeling it includes preparing several wireframe models such as topography surface model and ore body model the topography surface wireframe model can be designed using digital terrain model dtm tools in general these tools are used to create wireframe models of open undulating surfaces such as topography geological features fault surfaces lithology or mineralization contact surfaces open pit designs and open pit survey measurements the topography surface wireframe model is done using the topography contour strings object as a basis for the wireframe the next step is to create a closed volume wireframe model of the ore body using a wireframe linking toolbar a wireframe of the ore body is designed by clicking corresponding points the wireframe obtained is a closed volume containing both wireframe surfaces at each end and between each section string fig 8 13 there should not be any gaps nor holes in the wireframe volume it is essential to verify wireframes before calculating wireframe volumes evaluating wireframes for tons and average grades against drillholes or block models and or using wireframes for block modeling purposes otherwise unverified wireframes can potentially cause problems with wireframe volume calculations block modeling using wireframes or other processes that use wireframes as input after that volumes for closed volume such as an ore body can be calculated geological block modeling involves three steps a creating a waste block model below the topography surface wireframe b creating and ore body block model from a closed volume wireframe and c creating a combined ore body and waste block model for the first model it is necessary to establish the cell size parameters and other settings once these data are defined the model is shown in fig 8 14 similarly an ore model within the ore body s closed volume

wireframe object is created finally the extent of the ore and waste block model against the surface dtm and the ore body wireframe is combined then it is needed to check the ore body block model the process is carried out by visual methods or using summary statistics the aim of visually checking a block model against its wireframe is to search errors such as cells extending beyond the limits of the wireframe e g the cell center lies beyond the wireframe the surface may be damaged or contain holes regarding checking of the ore body block model using summary statistics the goal is to review the block model s numeric fields looking for errors such as absent data e g cells not flagged with the mineralization zone field records with missing values and unexpected minimum or maximum values e g coordinates or mineral grade values the last item in the geological modeling process is to combine the waste and ore block models because it is essential to have a single model for presentation economic optimization or evaluation purposes however it is important to note that combining block models can potentially result in very large files obviously block models that do not have the same block model definition e g block model prototype cannot be combined figure 8 16 shows the result of combining both models hereafter it is possible to optimize the resulting block model since the optimization combination of subcells within the limits of parent cells by one or more key fields typically results in a smaller file size the steps in the life cycle of a mineral deposit may be brie y summarized as follows 1 mineral exploration to discover a mineral deposit 2 feasibility study to prove its commercial viability 3 mine development establishment of the entire infrastructure 4 mining extraction of ore from the ground 5 mineral processing milling of the ore separation of ore minerals from gangue material separation of the ore minerals into concentrates e g copper concentrate separation and re nement of industrial mineral products 6 smelting recovering metals from the mineral concentrates 7 re ning purifying the metal 8 marketing shipping the product or metal concentrate if not smelted and re ned at the mine to the buyer e g custom smelter manufacturer 9 closure before a mine has reached the end of its life there has to be a closure management plan in place that details and costs the proposed closure strategies signi cant expenditure could be incurred with clean up and remediation of mining and smelting sites the costs of employee retrenchment and social and community implications the exploration step can be subdivided as follows i study phase choice of potential target study of demand supply commodity price trends available markets exploration cost draw up budget ii reconnaissance phase will start with a literature search and progress to a review of available remote

sensing and photogeological data leading to selection of favorable areas initial eld reconnaissance and land acquisition probably followed by airborne surveys geological mapping and prospecting geochemical and geophysical surveys and limited drilling see chapter 4 iii target testing detailed geological mapping and detailed geochemical and geophysical surveys trenching and pitting drilling see chapter 5 if successful this will lead to an order of magnitude study which will establish whether there could be a viable project that would justify the cost of progressing to a prefeasibility study iv pre feasibility major sampling and test work programs including mineralogical examination of the ore and pilot plant testing to ascertain the viability of the selected mineral processing option and likely recoverability see chapter 11 it evaluates the various options and possible combinations of technical and business issues v feasibility study drilling assaying mineralogical and pilot plant test work will continue the feasibility study con rms and maximizes the value of the preferred technical and business option identi ed in the prefeasibility study stage it is at the end of the order of magnitude study that the explorationists usually hand over to the mining geologists mineral processors and geotechnical and mining engineers to implement steps 1 to 9 typical time spans and costs might be stage i 1 2 years us 0 25m ii 2 years us 0 5 1 5m iii and iv 2 3 years us 2 5 50m v 2 years us 2 5 50m excluding actual capital cost for mine con struction some of these stages will overlap but this is unlikely to reduce the time involved and it can be expected that around 12 years will elapse between the start of the exploration program and the commencement of mine production in a number of cases the lead in time has been less but this has usually been the result of the involvement of favorable factors or a deliberate search for deposits particularly of gold which would have short lead in times the structure of the mining industry changed greatly in the 1990s and early 2000s with the decline in government funded mineral exploration particularly in centrally planned economies of central europe and the former ussr and the merging and globalization of many mining companies the producing section of the mining industry was dominated in 2002 by three companies mining a range of commodities bhp billiton rio tinto and anglo american and by alcoa an aluminum producer fig 1 9 other major companies concentrate on gold mining newmont mining barrick gold and anglogold ashanti platinum e g anglo american platinum and impala platinum and nickel production norilsk inco one major copper producing company corporacion nacional del cobre codelco is not shown as it is still owned by the chilean state other smaller mining companies produce at regional or national levels junior companies

are a major feature of the mineral exploration industry they are based largely in canada where more than 1000 companies are active in australia and to a lesser extent in the usa and europe their strategies are varied but can be divided into two subgroups one is exclusively involved in mineral exploration and aims to negotiate agreements with major companies on any deposits they discover and the other to retain at least a share of any discovery and to control the production of any discovery macdonald 2002 the dependence of these small companies on speculative activities has led to some taking extreme risks and giving the industry a bad name geographical factors may determine whether or not an orebody is economically viable in a remote location there may be no electric power supply or water supply roads railways houses schools hospitals etc all or some of these infrastructural elements will have to be built the cost of transporting the mine product to its markets may be very high and wages will have to be high to attract skilled workers 1 5 2 sustainable development new mines bring prosperity to the areas in which they are established but they are bound to have an environmental and social impact when production started at the neves corvo copper mine in southern portugal in 1989 it required a total labor force of about 1090 generally one mine job creates about three indirect jobs in the community in service and construction industries so the impact is clearly considerable such impacts have led to con icts over land use and opposition to the exploitation of mineral deposits by environmentalists particularly in the more populous of the developed countries the resolution of such con icts may involve the payment of compensation and planning for high closure costs or even the abandonment of projects a select committee 1982 stated whilst political risk has been cited as a barrier to investment in some countries environmental risk is as much of a barrier if not a greater in others opposition by environmentalists to exploration and mining was partially responsible for the abandonment of a major copper mining project in the snowdonia national park of wales as early as 1973 woodall 1992 has remarked that explorationists must not only prove their projects to be economically viable but they must also make them socially and therefore politically acceptable a major attempt to understand the problem and to suggest solutions has been made by the mining minerals and sustainable development project sponsored by most major mining companies mmsd 2002 from this it is clear that the concerns of local inhabitants must be addressed from an early stage if mine development is to be successful overzealous governments may demand so much tax that mining companies cannot make a reasonable pro t on the other hand some governments have encouraged mineral development with taxation incentives such as a waiver on tax during the

early years of a mining operation this proved to be a great attraction to mining companies in the irish republic in the 1960s and brought considerable economic gains to that country once an orebody is being exploited it has become a wasting asset and one day there will be no ore no mine and no further cash ow the mine as a company will be wound up and its shares will have no value in other words all mines have a limited life and for this reason should not be taxed in the same manner as other commercial undertakings when this is taken into account in the taxation structure of a country it can be seen to be an important incentive to investment in mineral exploration and mining in that country 1 5 4 political factors political risk is a major consideration in the selection of a country in which to explore in the 1970s and 1980s the major fear was nationalization with perhaps inadequate or even no compensation possible political turmoil civil strife and currency controls may all combine to increase greatly the nancial risks of investing in certain countries in the 1990s and 2000s perhaps more signi cant risks were long delays or lack of environmental permits to operate corruption and arbitrary changes in taxation one of the most useful sources of information on political risk in mining is the fraser institute in vancouver fraser institute 2003 it publishes an annual review of the investment attractiveness of many countries and regions based on a poll of mining company executives the attractiveness is a combination of mineral potential and policy potential some countries for example chile rank at the top of both indices whereas others such as russia have a very high mineral potential index but a very low policy potential index ore minerals are the minerals of economic interest for which the explorationist is searching they can be metallic or nonmetallic mineralogy is used to understand the relationships between the ore mineral and the uneconomic host rock for their eventual separation economic mineral deposits consist of every gradation from bulk materials or aggregates in which most of the rock or mineral is of commercial value to deposits of precious metals gold silver pgm from which only a few ppm or ppb in the case of diamond deposits are separated and sold the valuable mineral in one deposit may be a gangue mineral in another e g quartz is valuable in silica sands but is a gangue mineral in auriferous quartz veins thus the presentation of lists of ore and gangue minerals without any provisos as given in some textbooks can be very misleading to the beginner this may lead to an erroneous approach to the examination of mineral deposits i e what is recovered and what is discarded an alternative question is how can we process everything we are going to mine and market the products at a pro t there are few mineral operations where everything is mined gainfully fortunes can be made out of the was

te left by previous mining and smelting operations but not usually by the company that dumped it a good example of a mine where everything is mined is at the king s mountain operation in the tin spodumene belt of north carolina it is in the world s most important lithium producing area kunasz 1982 the spodumene occurs in micaceous granite pegmatites and in the mill the ore is processed to produce chemical grade spodumene and ceramic spodumene concentrates mica and feldspar concentrates and a quartz feldspar mix marketed as sandspar the amphibolite host rock is crushed sized and sold as road aggregate of course such comprehensive exploitation of all the material mined is not possible in isolated locations but too often the potential of waste material is overlooked a comprehensive mineralogical examination of a mineral deposit and its waste rocks may mean that additional valuable materials in the deposit are identi ed and the presence of deleterious substances detected this may add value if the project is ever brought to the production stage and will help to avoid embarrassing undervaluation ore minerals may be native metals elements of which gold and silver are examples or compounds of metals with sulfur arsenic tellurium etc such as lead sul de the mineral galena pbs or they may be carbonates silicates borates phosphates there are few common minerals that do not have an economic value in some mineralogical context or other some of the more important ore minerals are listed in table 2 1 and those which are often classi ed as gangue minerals in table 2 2 ore minerals may be classed as primary hypogene or secondary supergene hypogene minerals were deposited during the original period of rock formation or mineralisation supergene minerals were formed during a later period of mineralisation usually associated with weathering and other near surface processes leading to precipitation of the secondary minerals from descending solutions secondary mineralisation is superposed on primary mineralisation the grade increases and this is termed supergene enrichment when 2 2 mineralogical investigations before looking at some of the many methods that may be used the economic importance of these investigations will be emphasized by discussing brie y the importance of mineralogical form and undesirable constituents mineralogical form the properties of a mineral govern the ease with which existing technology can extract and re ne certain metals and this may affect the cut off grade see section 10 4 2 thus nickel is far more readily recovered from sul de than from silicate minerals and sul de minerals can be extracted down to about 0 5 whereas silicate minerals must assay about 1 5 to be economic tin may occur in a variety of silicate minerals such as stanniferous andradite ca 3 fe 2 si 3 o 12 and axinite ca fe mn al 2 bsi 4 o 15 oh from which it is not recoverable as well as in its main ore mineral

form cassiterite sno 2 aluminum is of course abundant in many silicate rocks but it must be usually in the form of hydrated aluminum oxides the rock called bauxite for economic recovery the mineralogy of the ore mineral will also place limits on the maximum possible grade of the concentrate for example in a mineral deposit containing native copper it is theoretically possible to produce a concentrate containing 100 cu but if the ore mineral chalcopyrite cufes 2 is the principal source of copper then the best concentrate would only contain 34 5 cu undesirable substances deleterious elements may be associated with both ore and gangue minerals for example tennantite cu 12 as 4 s 13 in copper ores can introduce unwanted arsenic and sometimes mercury into copper concentrates these like phosphorus in iron concentrates and arsenic in nickel concentrates will lead to custom smelters imposing nancial penalties or refusing the shipment the ways in which gangue minerals may lower the value of an ore are very varied for example an acid leach is normally employed to extract uranium from the crushed ore but if the carbonate calcite caco 3 is present there will be excessive acid consumption and the less effective alkali leach method may have to be used some primary tin deposits contain appreciable amounts of topaz which because of its hardness increases the abrasion of crushing and grinding equipment thus raising the operating costs to summarize the information that is required from a sample includes some or all of the following i the grade of the economic minerals ii the bulk chemical composition iii the minerals present iv the proportions of each of these and their chemical compositions v their grain size vi their textures and mineral locking patterns vii any changes in these features from one part of an orebody to another 2 2 1 sampling mineralogical investigations will lose much of their value if they are not based on systematic and adequate sampling of all the material that might go through the processing plant i e mineralized material and host rock the basics of sound sampling procedures are discussed in chapter 10 the material on which the mineralogist will have to work can vary from solid coherent rock through rock fragments and chips with accompanying nes to loose sand where there is considerable variation in the size of particles in the sample it is advantageous to screen sieve the sample to obtain particles of roughly the same size as these screened fractions are much easier to sample than the unsized material the mineralogist will normally subsample the primary samples obtained by geologists from the prospect to produce a secondary sample and this in turn may be further reduced in bulk to provide the working sample using techniques discussed in jones 1987 and recent technological innovations 2 2 2 mineral identi cation initial investigations should be made using the n

aked eye the hand lens and a stereobinocular microscope to i determine the ore types present and ii select representative specimens for thin and polished section preparation at this stage uncommon minerals may be identi ed in the hand specimen by using the determinative charts in mineralogical textbooks such as berry et al 1983 or the more comprehensive method in jones 1987 the techniques of identifying minerals in thin section are taught to all geologists and in polished sections to most and will not be described here for polished section work the reader is referred to craig and vaughan 1994 and ineson 1989 as well as the online manual of ixer and duller 1998 modern optical microscopes have signi cantly increased resolution and oil immersion is not often used in commercial laboratories simple microscope and scanning electron microscope sem methods are usually all that is required to effectively identify all the minerals in the samples x ray diffraction is used to identify clay mineral structure and properties and for mineral analysis and mineral abundance measurements through spectroscopic sensing modern x ray diffractometers can work well on solid specimens compacted powder pellets representing whole rocks or on a few grains on a smear mount multiple mounts can be automatically fed into the diffractometer the rock sample is normally powdered and packed into an aluminum holder it is then placed in the diffractometer and bombarded with x rays the diffracted rays are collected by a detector and the information relayed to a computer where it is converted to d values of speci c intensities this information can then be shown graphically in the form of a diffraction pattern or diffractogram the diffractograms from the unknown sample are then matched against a database of 70 000 recorded phases for mineral identi cation the latest instruments allow for rapid recognition of the entire spectrum of the sample in minutes using a computer to match patterns and identify the minerals present electron and ion probe microanalyzers with this equipment a beam of high energy electrons is focused on to about 1 2 m 2 of the surface of a polished section or a polished thin section ores are crushed during milling to liberate the various minerals from each other section 2 2 3 and for concentration a valuable mineral has to be reduced to less than its liberation size in order to separate it from its surrounding gangue crushing and grinding of rock is expensive and if the grain size of a mineral is below about 0 05 mm the cost may well be higher than the value of the liberated constituents in addition there are lower limits to the degree of milling possible dictated by the separation processes to be employed because these are most effective over certain grain size ranges e g magnetic separation 0 02 2 5 mm froth otation 0 01 0 3 mm electrostatic separation 0 12 1 4 mm in fig 2 2 a number of intergrowth pattern

s are illustrated further crushing of the granular textured grains in a will give good separation of ore black from gangue this is an ideal texture from the processing point of view in b further crushing of the tiny pyrite grain veined by chalcopyrite black is out of the question and this copper will be lost to the tailings the chalcopyrite black occurring as spheroids in sphalerite grains c is too small to be liberated and will go as a copper loss into the zinc concentrate the grain of pyrite coated with supergene chalcocite black in d will during froth otation carry the pyrite as a diluting impurity into the copper concentrate the grain is too small for separation of the two minerals by crushing it must be noted that the market price for a metal does not apply fully or directly to concentrates the purchase terms quoted by a custom smelter are usually based on a nominal concentrate grade and lower concentrate grades are penalized accord ing to the amount by which they fall below the contracted grade exsolution textures commonly devalue ores by locking up ore minerals and by introducing impurities in e the tiny ame shaped exsolution bodies of pentlandite black in the pyrrhotite grain will go with the pyrrhotite into the tailings and the ilmenite bodies black in magnetite f are likewise too small to be liberated by further grinding and will contaminate the magnetite concentrate if this magnetite is from an ilmenite orebody then these interlocked ilmenite bodies will be a titanium loss the size shape and nature of ore deposits affects the workable grade large low grade deposits which occur at the surface can be worked by cheap open pit methods whilst thin tabular vein deposits will necessitate more expensive underground methods of extraction open pitting aided by the savings from bulk handling of large daily tonnages say 30 kt has led to a trend towards the large scale mining of low grade orebodies as far as shape is concerned orebodies of regular shape can generally be mined more cheaply than those of irregular shape particularly when they include barren zones for an open pit mine the shape and attitude of an orebody will also determine how much waste has to be removed during mining the waste will often include not only overburden waste rock above the orebody but also waste rock around and in the orebody which has to be cut back to maintain a safe overall slope to the sides of the pit see section 11 2 1 before discussing the nature of ore bodies we must learn some of the terms used in describing them if an orebody viewed in plan is longer in one direction than the other we can designate this long dimension as its strike fig 3 1 the inclination of the orebody perpendicular to the strike will be its dip and the longest dimension of the orebody its axis the plunge of the axis is measured in the vertical plane abc but its pitch or rake can be measured in any other plane the usual c

hoice being the plane containing the strike although if the orebody is fault controlled then the pitch may be measured in the fault plane the meanings of other terms are self evident from the gure it is possible to classify orebodies in the same way as we divide up igneous intrusions according to whether they are discordant or concordant with the lithological banding often bedding in the enclosing rocks considering discordant orebodies rst this large class can be subdivided into those orebodies which have an approximately regular shape and those which are thoroughly irregular in their outlines tabular orebodies these bodies are extensive in two dimensions but have a restricted development in their third dimension in this class we have veins sometimes called ssure veins and lodes fig 3 2 these are essentially the same and only the term vein is now normally used veins are often inclined and in such cases as with faults we can speak of the hanging wall and the footwall veins frequently pinch and swell out as they are followed up or down a stratigraphical sequence fig 3 2 this pinch and swell structure can create dif culties during both exploration and mining often because only the swells are workable if these are imagined in a section at right angles to that in fig 3 2 it can be seen that they form ribbon ore shoots veins are usually developed in fracture systems and therefore show regularities in their orientation throughout the ore eld in which they occur hanging wall footwall 20 m flat thick impervious shale limestone shale limestone shale sandstone fig 3 2 vein occupying a normal fault and exhibiting pinch and swell structure giving rise to ribbon ore shoots the development of a at beneath impervious cover is shown also the in lling of veins may consist of one mineral but more usually it consists of an intergrowth of ore and gangue minerals the boundaries of vein orebodies may be the vein walls or they may be assay boundaries within the veins tubular orebodies these bodies are relatively short in two dimensions but extensive in the third when vertical or subvertical they are called pipes or chimneys when horizontal or subhorizontal mantos the spanish word manto is inappropriate in this context for its literal translation is blanket it is however rmly entrenched in the english geological literature the word has been and is employed by some workers for at lying tabular bodies but the perfectly acceptable word at fig 3 2 is available for these therefore the reader must look carefully at the context when he or she encounters the term manto mantos and pipes may branch and anastomose and pipes frequently act as feeders to mantos in eastern australia along a 2400 km belt from queensland to new south wales there are hundreds of pipes in and close to granite intrusions most have quartz llings and some are mineralized with bismuth molybdenum tungsten and tin an example is shown in f

ig 3 3 pipes may be of various types and origins mitcham 1974 in llings of mineralized breccia are particularly common a good example being the copper bearing breccia disseminated deposits in these deposits ore minerals are peppered throughout the body of the host rock in the same way as accessory minerals are disseminated through an igneous rock in fact they often are accessory minerals a good example is that of diamonds in kimberlites in other deposits the disseminations may be wholly or mainly along close spaced veinlets cutting the host rock and forming an interlacing network called a stockwork fig 3 4 or the economic minerals may be disseminated through the host rock along veinlets whatever the mode of occurrence mineralisation of this type generally fades gradually outwards into subeconomic mineralisation and the boundaries of the orebody are assay limits they are therefore often irregular in form and may cut across geological boundaries the overall shapes of some are cylindrical others are caplike whilst the mercury bearing stockworks of dubnik in slovakia are sometimes pear shaped stockworks most commonly occur in porphyritic acid to intermediate plutonic igneous intrusions but they may cut across the contact into the country rocks and a few are wholly or mainly in the country rocks disseminated deposits produce most of the world s copper and molybdenum porphyry coppers and disseminated molybdenums and they are also of some importance in the production of tin gold silver see chapter 16 mercury and uranium porphyry coppers form some of the world s monster orebodies grades are generally 0 4 1 5 cu and tonnages 50 5000 mt irregular replacement deposits many ore deposits have been formed by the replacement of pre existing rocks particularly carbonaterich sediments e g magnesite deposits these replacement processes often occurred at high temperatures at contacts with medium sized to large igneous intrusions such deposits have therefore been called contact metamorphic or pyrometasomatic however skarn is now the preferred and more popular term the orebodies are characterized by the development of calc silicate minerals such as diopside wollastonite andradite garnet and actinolite these deposits are extremely irregular in shape fig 3 5 tongues of ore may project along any available planar structure bedding joints faults etc and the distribution within the contact aureole is often apparently capricious structural changes may cause abrupt terminasurface tion of the orebodies the principal materials produced from skarn deposits are iron copper tungsten graphite zinc lead molybdenum tin uranium and talc concordant orebodies sedimentary host rocks concordant orebodies in sediments are very important producers of many different metals being particularly important for base metals and iron and are of course concordant with the bedding they may be an integral part of the st

ratigraphical sequence as is the case with phanerozoic ironstones or they may be epigenetic in llings of pore spaces or replacement orebodies usually these orebodies show a considerable development in two dimensions i e parallel to the bedding and a limited development perpendicular to it fig 3 6 and for this reason such deposits are referred to as stratiform this term must not be confused with strata bound which refers to any type or types of orebody concordant or discordant which are restricted to a particular part of the stratigraphical column thus the veins pipes and ats of the southern pennine ore eld of england can be designated as strata bound as they are virtually restricted to the carboniferous limestone of that region a number of examples of concordant deposits which occur in different types of sedimentary rocks will be considered limestone hosts limestones are very common host rocks for base metal sul de deposits in a dominantly carbonate sequence ore is often developed in a small number of preferred beds or at certain sedimentary interfaces these are often zones in which the permeability has been increased by dolomitization or fracturing when they form only a minor part of the stratigraphical succession limestones because of their solubility and reactivity can become favorable horizons for mineralisation for example the lead zinc ores of bingham utah occur in limestones which make up 10 of a 2300 m succession mainly composed of quartzites argillaceous hosts shales mudstones argillites and slates are important host rocks for concordant orebodies which are often remarkably continuous and extensive in germany the kupferschiefer of the upper permian is a prime example this is a copper bearing shale a meter or so thick which at mansfeld occurred in orebodies which had plan dimensions of 8 16 36 and 130 km 2 mineralisation occurs at exactly the same horizon in poland where it is being worked extensively and across the north sea in north eastern england where it is subeconomic the world s largest single lead zinc orebody occurs at sullivan british columbia the host rocks are late precambrian argillites above the main orebody fig 3 6 there are a number of other mineralized horizons with concordant mineralisation this deposit appears to be syngenetic and the lead zinc and other metal sul des form an integral part of the rocks in which they occur the orebody occurs in a single generally conformable zone 60 90 m thick and runs 6 6 pb and 5 9 zn other metals recovered are silver tin cadmium antimony bismuth copper and gold this orebody originally contained at least 155 mt of ore other good examples of concordant deposits in argillaceous rocks or slightly metamorphosed equivalents are the lead zinc deposits of mount isa queensland many of the zambian copperbelt deposits and the copper shales of the white pine mine michigan arenaceous hosts not all the zambian coppe

rbelt deposits occur in shales and metashales some bodies occur in altered feldspathic sandstones such as mufulira which consists of three extensive lenticular orebodies stacked one above the other and where the ore reserves in 1974 stood at 282 mt assaying 3 47 cu the largest orebody has a strike length of 5 8 km and extends several kilometers down dip many other concordant sandstone hosted orebodies occur around the world such as those in desert sands red bed coppers which are very important in china where they make up nearly 21 of the stratiform copper reserves of that country chen 1988 many mechanical accumulations of high density minerals such as magnetite ilmenite rutile and zircon occur in arenaceous hosts usually taking the form of layers rich in heavy minerals in pleistocene and holocene sands as the sands are usually unlithi ed the deposits are easily worked and no costly crushing of the ore is required these orebodies belong to the group called placer deposits beach sand placers supply much of the world s titanium zirconium thorium cerium and yttrium they occur along present day beaches or ancient beaches where longshore drift is well developed and frequent storms occur economic grades can be very low and sands running as little as 0 6 heavy minerals are worked along australia s eastern coast rudaceous hosts alluvial gravels and conglomerates also form important recent and ancient placer deposits alluvial gold deposits are often marked by white runs of vein quartz pebbles as in the white channels of the yukon the white bars of california and the white leads of australia such deposits form one of the few types of economic placer deposits in fully lithi ed rocks and indeed the majority of the world s gold is won from precambrian deposits of this type in south africa chemical sediments sedimentary iron and manganese formations and evaporites occur scattered through the stratigraphical column where they form very extensive beds conformable with the stratigraphy igneous host rocks volcanic hosts the most important deposit type in volcanic rocks is the volcanicassociated massive sul de see chapter 15 or oxide type the sul de variety often consists of over 90 iron sul de usually as pyrite they are generally stratiform bodies lenticular to sheetlike fig 3 8 developed at the interfaces between volcanic units or at volcanic sedimentary interfaces with increasing magnetite content these sul de ores grade into massive oxide ores of magnetite and or hematite such as savage river in tasmania fosdalen in norway and kiruna in sweden they can be divided into three classes of deposit a zinc lead copper b zinc copper and c copper typical tonnages and copper grades are 0 5 60 mt and 1 5 but these are commonly polymetallic deposits often carrying other base metals and signi cant precious metal values which make them plum targets for exploration e g neves corvo see section 1 2 3 me

tal and mineral prices the most important host rock is rhyolite and lead bearing ores are only associated with this rock type the copper class is usually but not invariably associated with ma c volcanics massive sul de deposits commonly occur in groups and in any one area they are found at one or a restricted number of horizons within the succession see section 15 2 5 these horizons may represent changes in composition of the volcanic rocks a change from volcanism to sedimentation or simply a pause in volcanism there is a close association with volcaniclastic rocks and many orebodies overlie the explosive products of rhyolite domes these ore deposits are usually underlain by a stockwork that may itself be ore grade and which appears to have been the feeder channel up which mineralizing uids penetrated to form the overlying massive sul de deposit all these relationships are of great importance in the search for this orebody type plutonic hosts many plutonic igneous intrusions possess rhythmic layering and this is particularly well developed in some basic intrusions usually the layering takes the form of alternating bands of ma c and felsic minerals but sometimes minerals of economic interest such as chromite magnetite and ilmenite may form discrete mineable seams within such layered complexes these seams are naturally stratiform and may extend over many kilometers as is the case with the chromite seams in the bushveld complex of south africa and the great dyke of zimbabwe another form of orthomagmatic deposit is the nickel copper sul de orebody formed by the sinking of an immiscible sul de liquid to the bottom of a magma chamber containing ultrabasic or basic magma these are known as liquation deposits and they may be formed in the bottom of lava ows as well as in plutonic intrusions the sul de usually accumulates in hollows in the base of the igneous body and generally forms sheets or irregular lenses conformable with the overlying silicate rock from the base upwards massive sul de gives way through disseminated sul des in a silicate gangue to lightly mineralized and then barren rock fig 3 9 metamorphic host rocks apart from some deposits of metamorphic origin such as the irregular replacement deposits already described and deposits generated in contact metamorphic aureoles e g wollastonite andalusite garnet graphite metamorphic rocks are important for the metamorphosed equivalents of deposits that originated in sedimentary and igneous rocks and which have been discussed above residual deposits these are deposits formed by the removal of nonore material from protore rock in which an initial but uneconomic concentration of minerals is present that may by further natural processes be upgraded to form ore for example the leaching of silica and alkalis from a nepheline syenite may leave behind a surface capping of hydrous aluminum oxides bauxite some residual bauxites occur at the present surface o

thers have been buried under younger sediments to which they form conformable basal beds the weathering of feldspathic rocks granites arkoses can produce important kaolin deposits which in the cornish granites of england form funnel or trough shaped bodies extending downwards from the surface for as much as 230 m other examples of residual deposits include some laterites suf ciently high in iron to be worked and nickeliferous laterites formed by the weathering of peridotites 3 2 wall rock alteration many ore deposits particularly the epigenetic ones may have beside or around them a zone or zones of wall rock alteration this alteration of the host rock is marked by color textural mineralogical or chemical changes or any combination of these the areal extent of the alteration can vary considerably sometimes being limited to a few centimeters on either side of a vein at other times forming a thick halo around an orebody and then since it widens the drilling target it may be of considerable exploration value hoeve 1984 estimated that the drilling targets in the uranium eld of the athabasca basin in saskatchewan are enlarged by a factor of 10 20 times by the wall rock alteration one of te aims of the planning stage is to identify areas for reconnaissance and to do this we must have some idea of how the materials sought relate to geological factors including geophysics and geochemistry this is best achieved by setting up a model or models of the type of deposit sought but what is a model the term has been de ned in various ways but a useful one is that of functional idealization of a real world situation used to aid in the analysis of a problem as such it is a synthesis of available data and should include the most informative and reliable characteristics of a deposit type identi ed on a variety of scales and including de nition of the average and range of each characteristic adams 1985 it is therefore subject to uncertainty and change each new discovery of an example of a deposit type should be added to the data base in mineral deposit models there are two main types which are often combined the empirical model based on deposit descriptions and a genetic model which explains deposits in term of causative geological processes the genetic model is necessarily more subjective but can be more powerful as it can predict deposits not contained in the descriptive data base another type of model which is extremely useful for preliminary economic evaluations is a gradetonnage model this accumulates grade and tonnage data for known deposits and from this it is possible to estimate the size and grade of an average or large deposit and the cash ow if one were found examples of this type of modeling are given by gorman 1994 for south american gold and copper deposits cost curves can also be calculated for differing deposit types examples for copper fig 3 10 show the low cost of producing from porphyry copper deposi

ts and the economies of scale from large production relative to sedimentary copper and volcanicassociated massive sul de deposits the widely accepted terms used for the early stages of exploration are planning and reconnaissance phases these phases cover the stages leading to the selection of an area for detailed ground work this is usually the point at which land is acquired the planning stage covers the selection of commodity type of deposit exploration methods and the setting up of an exploration organization the process of selecting drill targets within license blocks we term target selection and that of drilling target testing the deposit is then at the stage of predevelopment followed by a feasibility study the exploration players private sector most mineral exploration in developed countries is conducted by companies with a substantial capital base generated either from existing mineral production or from investors on stock markets the size of the company can range from major multinational mining companies such as rio tinto plc or anglo american corporation with operations on several continents to small venture capital companies usually known as a junior company with one or two geologists exploration by individual prospectors has been an important factor in countries with large unexplored areas and liberal land tenure laws e g canada australia and brazil here you can still meet the grizzled prospector or garimpeiro although they usually lack the sophisticated training of the corporate geologist this can be compensated for by a keen eye and the willingness to expend a little boot leather state organizations in more centrally directed economies most exploration is carried out by state run companies geological surveys and often in the case of developing countries international aid organizations the role of a geological survey usually includes some provision of information on mineral exploration to government and the private sector usually this takes the form of reconnaissance work by contrast the soviet ministry of geology had until 1991 exclusive prospecting rights in the former ussr although exploration was carried out by a wide variety of organizations at the union federal and republic levels in china exploration is undertaken by a number of state and provincial groups including the army these two groups essentially explore in similar ways although state enterprises are more constrained by political considerations and need not necessarily make a pro t the remainder of the chapter will be devoted to private sector organizations although much may be applicable to state organizations 4 1 exploration planning mineral exploration is a long term commitment and there must be careful planning of a company s long term objectives this should take particular regard of the company s resources and the changing environment in which it operates riddler 1989 the key factors are 1 location of demand for products

this will depend on the areas of growth in demand for metals the most obvious areas are the industrializing countries of the paci c rim and who are resource de cient china has assumed particular importance since the late 1990s for a wide range of commodities 2 metal prices price cycles should be estimated as far as possible and supply and demand forecast see section 1 2 3 3 host country factors the choice of country for operation is important in an industry which has seen substantial nationalization such as copper in the democratic republic of congo and zambia and coal in the uk the standing of foreign investment the degree of control permitted percentage of pro ts remittable to the home country and most of all government stability and attitude are important other factors are availability of land security of tenure and supply of services and skilled labor see section 1 4 4 the structure of the mining industry barriers to the entry of new producers are competition from existing producers and the need for capital to achieve economies of scale after the initial corporate planning usually by senior executives an exploration strategy must be chosen a budget allocated and desirable deposit type s de ned the choice of exploration strategy varies considerably between companies and depends on the objects of the company and its willingness to take risks for new entrants into a country the choice is between exploration by acquisition of existing prospects or grass roots i e from scratch exploration acquisition requires the larger outlay of capital but carries lower risk and has potentially a shorter lead time to production acquisitions of potential small producers are particularly attractive to the smaller company with limited cash ow from existing production potential large producers interest larger companies which have the capital necessary to nance a large project this has been particularly marked in the early years of the twenty rst century in the consolidation of the gold industry into a few large producers that have devoured the medium sized producers larger companies tend to explore both by acquisition and by grass roots methods and often nd that exploration presence in an area will bring offers of properties submittals existing producers have the additional choice of exploring in the immediate vicinity of their mines where it is likely that they will have substantial advantages in cost saving by using existing facilities most of the following section refers to grass roots exploration although evaluation of potential acquisitions could run in parallel the key to exploration organization is to have the best available staff and adequate nance in order to create con dence throughout the organization woodall 1984 sillitoe 1995 2000 a number of factors that characterize a successful exploration team have been recognized by snow and mackenzie 1981 regan 1971 and discussed in detail by white

1997 1 high quality staff and orientation towards people successful organizations tend to provide more in house training 2 sound basis of operations the organization works within corporate guidelines towards objectives 3 creative and productive atmosphere the group encourages independent creative and innovative thinking in an environment free from bureaucratic disruption 4 high standard of performance integrity and ethics 5 entrepreneurial acumen innovation is fostered in a high risk high reward environment 6 morale and team spirit high morale enthusiasm and a can do attitude 7 the quality of communication is high the top brass are aware of the ideas of geologists 8 pre development group successful organizations are more likely to have a specialist group responsible for the transition of a deposit from exploration to development all these points make that management must consist with considerable of exploration if these are the optimum characteristics of an exploration group is there an optimum size and what structure should it have studies such as those of holmes 1977 show that the most effective size is in the range seven to ten geologists larger organizations tend to become too formalized and bureaucratic leading to inef ciency whereas small groups lack the budgets and the manpower to mount a successful program for the large mining group which wishes to remain competitive while spending a large budget the solution is to divide its explorationists into semiautonomous groups exploration groups can be organized on the basis of geographical location or of deposit type the advantage of having deposit specialists is that in depth expertise is accumulated however the more usual arrangement is to organize by location with geologists in each region forming specialist subgroups at the reconnaissance stage most work will be carried out in of ces located in the national head of ce or state of ce but as exploration focuses in more detail smaller district of ces can be opened in a company with existing production there may be close liaison with mines and engineering divisions exploration costs are considered in two ways i as an expenditure within an organization and ii within the context of a project it is usually the exploration manager that considers the former but it is as a geologist on a speci c exploration project that one becomes involved in the latter corporate exploration expenditure finance for corporate exploration is derived from two main sources revenue from existing production and by selling shares on the stock market in the rst case the company sets aside a percentage of its before tax pro ts for exploration the decision as to the percentage set aside is based upon how much the company wishes to keep as capital for their running costs as dividend for their shareholders and for taxes exploration costs may range from 1 to 20 of the annual corporate cash ow but for large diversi ed co

mpanies this is an average 2 5 of sales and 6 for gold companies crowson 2003 this may be anything between us 0 5 million to 100 million per annum depending upon the size of the company and the size of the deposit for which they are searching table 4 1 for producing companies most exploration can be written off against tax the smaller company is at a disadvantage in that money must be raised from shareholders this is easy in times of buoyant share prices for example about c2 billion were raised in the late 1980s for gold exploration in canada largely on the vancouver stock exchange this was aided by ow through schemes which enabled share purchasers to offset this against tax liabilities in a similar way but without tax breaks about us 100 million was raised on the irish stock exchange from 1983 to 1989 gardiner 1989 at the peak of the 1996 boom 1 1 billion was raised in one year on the vancouver stock exchange this was through initial public offerings of companies and private placements to individuals and investment funds hefferman 1998 although major mining groups should be able to maintain consistent budgets and avoid business cyclicity there seems little evidence of this in a study of major groups eggert 1988 demonstrated that spending was linked to income and therefore metal prices but lagged about 18 months behind the changes in income fig 4 3 the overall budget is then subdivided for example a multinational corporation may have several regional exploration centers each of which may have anything from one or two persons to a fully equipped of ce with up to 50 people employed the budget for the latter must include the salaries equipment of ce rentals and vehicular leases before a single geologist sets foot in the eld each project would be given a percentage of the regional of ce s budget e g exploration for coal 20 base metals 20 uranium 15 gold 25 and industrial minerals 20 particular exploration projects then have to compete for funds if a particular project is successful then it will attract additional spending this distribution of funds is carried out on a regular basis and is usually coupled with a technical review of exploration projects in which the geologist in charge of a project has to account for money spent and put forward a bid for further funding careful control of funds is essential and usually involves the nomination of budget holders and authorization levels for example the exploration manager may be able to authorize expenditure of 100 000 but a project geologist only 2000 so all drilling accounts will be sent to head of ce whereas the geologist will deal with vehicle hire and eld expenses in this case written authorization from the exploration manager would also be required before drilling starts summary accounts will be kept in head of ce under a quali ed accountant or bookkeeper and will be subject to regular audit by external accountants for most com

panies global expenditure on exploration will be included in annual accounts and will be written off against the year s income project basis in order to contain costs and provide a basis for future budgeting costs will be calculated for each exploration project rstly to monitor spending accurately and secondly so that the expenses can be written off against production if exploration is successful or if the project is sold to another company budgets are normally calculated on a yearly basis within which projects can be allocated funds on a monthly basis at the desk study stage the main costs are salaries of staff and these can be calculated from a nominal staff cost per month the average of the salaries is usually multiplied by two to cover pensions housing costs and secretarial support other support costs must be included such as vehicles and helicopter transport in remote areas direct costs of exploration are easier to estimate and include geochemistry remote sensing and geophysical costs these can be easily obtained by asking for quotations from contractors perhaps a more contentious matter is the allocation of overhead costs to each project these cover management time and will include the time of head of ce staff who review projects for presentation to board level management often these can be frighteningly large e g the costs of keeping a senior geologist in a metropolitan center will be much larger than in a small town table 4 2 shows a worksheet for the calculation of budget costs and table 4 3 gives an example of a completed budget and typical costs for reconnaissance programs 4 2 desk studies and reconnaissance 4 2 1 desk studies once the exploration organization is in place initial nance budgeted and target deposit type selected then desk studies can start and areas can be selected for reconnaissance but on what basis the rst stage in a totally new program is to acquire information about the areas selected besides background information on geology data on the occurrence of currently producing mines and prospects and their economic status are essential this information will normally be based largely on published material but could also include open le material from geological surveys and departments of mines data from colleagues and from consultants with particular expertise in the area concerned background geological information is available for most areas in the world although its scale and quality vary considerably in some parts of europe geological maps are published at 1 50 000 and manuscript eld sheets at 1 10 000 are available in less populated parts of the world such as canada or australia the base cover is 1 250 000 with more detailed areas at 1 100 000 for the mineral exploration geologist the published geological data will only be a beginning and he or she will interpret the geology using the geological features de ned in the deposit model this is best achieved by starting with a syn

optic view of the geology from satellite imagery unless the area is extensively vegetated this is likely to be from landsat or spot imagery see chapter 6 landsat has the added advantage of highlighting areas of hydrothermal alteration within arid areas if processed correctly in areas of dense vegetation side looking radar can be used for example most of amazonian brazil has been mapped in this way for smaller areas air photography provides better resolution often at considerably less cost although air photographs are still regarded as top secret in some less developed countries in spite of the availability of satellite information besides surface mapping familiar to most geologists a number of other sources of information on regional geology are widely used in exploration an invaluable addition to surface regional geology is the use of regional geophysics see chapter 7 airborne magnetics radiometrics and regional gravity data are available for much of the developed world and help in re ning geological interpretation and particularly in mapping deep structures for example a belt of the superior province in northern manitoba which hosts a number of major nickel deposits including the large deposit at thompson can be clearly followed under palaeozoic cover to the south fig 4 4 regional seismic data are helpful but are usually only available if oil companies donate them to the public domain specially commissioned seismic surveys have greatly helped in deciphering the subsurface geology of the witwatersrand basin see section 14 5 4 subsurface interpretations of geophysical information can be checked by linking them with information from any available deep drill hole logs regional geochemical surveys see section 8 4 also provide much information in areas of poor outcrop and have de ned major lithological provinces covered by boulder clay in finland the sources of information for mineral occurrence localities are similar to those for regional geology geological surveys usually have the most comprehensive data base within a country and much of this is normally published e g the summary of uk mineral potential of colman 2000 many surveys have collated all the mineral occurrences within their country and the results are available as maps reports or even on computerized databases two useful types of maps are mineral occurrence maps and metallogenic maps many of which are now available in digital format the former type merely shows the location of the occurrences whereas the latter attempts to show the form of the deposit and associated elements overlain on background geology using gis see section 9 2 overlays of the mineral prospects with geology will provide clues to regional controls on mineralisation at this point some economic input is required as it is often the case that signi cant prospects have different controls from weakly mineralized occurrences the sort of economic information that is useful are

the grades and tonnages mined recovery methods and the reasons for stopping mining this can be obtained from journals or from company reports an example of a desk study is the recognition of target areas for epithermal gold deposits in western turkey here mineral exploration increased signi cantly after 1985 due to the reform of turkish mining laws and the ability of non turkish mining companies to obtain a majority shareholding in any discovery western turkey is of interest as its geological setting is similar to eastern nevada see section 16 4 with extension and graben formation in the miocene accompanied by extensive volcanism and much current hot spring activity in addition a cursory glance at the metallogenic map of europe shows that a number of gold occurrences as well as other elements such as arsenic antimony and mercury which are often associated with epithermal activity are present fig 4 5 the mineral map of turkey erse en 1989 provides further information on reserves at several of these localities the compiler must test this information against the epithermal model in which gold is likely to be associated with graben bounding faults or volcanics most of the gold occurrences shown in western turkey are within high grade metamorphic rocks and represent metamorphosed quartz veins of little interest the aim of reconnaissance is to evaluate areas of interest highlighted in the desk study rapidly and to generate other previously unknown targets preferably without taking out licenses in areas of reasonable outcrop the first stage will be to check the geology by driving along roads or from the air if ground access is impossible a considerable number of disseminated gold prospects have been found by helicopter follow up of landsat data processed to highlight argillic alteration and siliceous caps in arid areas particularly in chile airborne geology can be extremely effective in solving major questions quickly but it is expensive us 500 per hour and is best undertaken by experienced geologists with specific problems to solve in any case a preliminary visit to the field should be made as soon as practicable to check the accessibility of the area examine on the ground some of the data emerging from the desk study and check on competitor activity reconnaissance techniques can be divided into those which enable a geologist to locate mineral prospects directly and those which provide background information to reduce the search area airborne geophysics and stream or lake sediment geochemistry are the principal tools for directly detecting mineralisation perhaps the most successful of these has been the use of airborne electromagnetic techniques in the search for massive sulfide deposits within the glaciated areas of the canadian shield this has led to the discovery of a number of deposits such as kidd creek see section 15 3 2 by drilling the airborne anomalies after very little ground work however each me

thod has drawbacks in the case of airborne electromagnetic techniques it is the inability to distinguish base metal rich sulfides from pyrite and graphite and interferences from conductive overburden airborne radiometrics have been very successful in finding uranium deposits in nonglaciated areas and led to the discovery of deposits such as ranger 1 and yeelirrie in australia dunn et al 1990a b in glaciated areas radiometric surveys have found a number of boulder trains which have led indirectly to deposits in areas of residual overburden and active weathering stream sediment sampling has directly located a number of deposits such as bougainville in papua new guinea but it is more likely to highlight areas for ground follow up and licensing the term land is deliberately used as the actual legal requirements for exploration and mining varies from country to country what the explorer needs to acquire is the right preferably exclusive to explore and to mine a deposit if the exploration is successful normally a company will obtain the right to explore the property for a particular period of time and the option to convert this into a right to mine if desired in return for an annual payment and in some cases the agreement to expend a minimum amount on exploration and to report all results unfortunately most legal systems are extremely complicated and the explorer may not be able to obtain the exact right that he or she requires for example gold or energy minerals may be excluded and the right to the surface of the land surface rights may be separate from the right to mine mineral rights two end member legal systems can be distinguished as far as mineral rights are concerned the first in which all mineral rights are owned by the state and the explorer can mine with no regard to the current occupier of the surface rights and the second in which all mineral and surface rights are privately owned the first normally results from governmental decree or revolution whereas the second is typical of many former british colonies in the private situation for example in britain the company s lawyer will negotiate with a private mineral rights owner and obtain an exploration or option agreement under which the company will be able to explore for a minimum period normally 3 years and then be able to renew the option or to buy the mineral rights for a fixed sum normally in excess of the free market value in exchange the mineral rights owner will receive a fixed annual sum option payment and compensation for any damage to the surface if he or she owns the surface rights if the surface rights are separately owned then an agreement must be made with that owner in the case of britain the rights to gold are owned by the crown and must be covered in a further separate agreement there is no legal obligation to report the results to government although summary drillhole results must be reported to the british geological survey most physi

cal exploration of any significance and drilling of greater than 28 days duration requires consent from the local planning authority state model in the case of state ownership the state will normally own the mineral rights and be able to grant access to the surface in this case application for an exploration license will usually be made to the department of mines the size of the exploration area may be fixed for example the law in western australia limits a 2 year prospecting license to 200 ha although a 5 year exploration license can cover between 10 and 200 km2 annual work commitments on the former are a40 ha 1 and a300 km 2 on the latter mining leases are granted for a renewable period of 21 years with a maximum area of 1000 ha normally in areas with state ownership a full report of exploration results must be filed to the mines department every year and at the termination of the lease such reports often provide information for future exploration as well as data for government decision making new mineral laws an example of a new mineral law designed to encourage exploration is the 1985 law of turkey under this exploration licenses are granted for 30 months these can be converted into pre operation licenses for 3 years and then into an operating or mining license the cost of an exploration license in 1992 was 4000 turkish lira us 0 10 ha 1 which is refundable when the license is relinquished the rights of small miners are protected by a right of denunciation under which any turkish citizen who can demonstrate a previous discovery in the area can claim 3 of the gross profit the whole operation is policed by a unit in the geological survey which uses a computerized system to monitor license areas problem countries in some countries the rule of law is less secure for example following the collapse of the soviet union it was not clear who was responsible for or owned mineral rights in the newly created countries or in russia deposits had been explored by state financed organizations which were left without funds and effectively privatized although these organizations were keen to sell rights to the deposits it was by no means certain that national governments recognized their title even when title could be agreed some governments tore up agreements without compensation when they realised the value of the deposits an example of this confusion was the grib diamond pipe in northern russia which was discovered by a junior north american company in 1996 and worth more than 5 billion in situ see section 17 1 6 the junior was in a 40 joint venture with a russian expedition which held the license subsequent to the discovery the junior company was unable to get the license transferred to a new joint venture company between them and the russian expedition as had been previously understood this was probably partly because the assets of the expedition had in the mean time been taken over by a major russian oil comp

any and a russian entrepreneur a few joint ventures have been successful under these conditions notably those in which governments have a significant stake a company 67 owned by the government of kyrgyzstan and 33 by cameco corporation of canada now centerra gold commissioned and operates the large kumtor gold mine in central asia legal advice is a virtual necessity in land acquisition and most exploration groups have a lawyer or land person on the staff or on a retainer if legal tenure is insecure then all exploration effort may be wasted and all revenue from the property go elsewhere the lawyer will also be responsible for checking the laws that need to be observed e g information from drillholes may need to be reported to government corporate administration should be checked so that there is no insider dealing or any activities that could be considered unethical a famous recent case was that in which lac minerals lost control of part of the large and profitable hemlo deposit in ontario it was alleged that lac minerals had bought claims from the widow of a prospector after receiving confidential information from another company corona corp and in spite of a verbal agreement not to stake that ground besides losing control of the deposit lac was faced with a large legal bill a more recent example was the dispute between western mining corporation and savage exploration pty ltd over control of the ernest henry deposit in northern queensland western mining 1993 leases in the area including a tenement named ml2671 had originally been pegged in 1974 by savage exploration for iron ore on the basis of the results of a government aeromagnetic survey in 1989 western mining decided to explore the area for base metals and obtained information in the public domain including the government airborne geophysics when western mining selected areas for further work they found that much of the land was held by hunter resources ltd and therefore entered into a joint venture with hunter but operated by western mining one of the areas targeted for further work by the joint venture was in the general area of ml2671 as described in the mines department files a baseline was pegged in july 1990 at 100 m intervals and crossed the described position of ml2671 although no pegs were seen on the ground to indicate the position of the lease a magnetic survey was undertaken including readings within the described area of ml2671 and an initial tem survey in august 1990 savage exploration was approached in march 1991 and agreement made over the terms of an option by which the western mining hunter joint venture could acquire a number of leases including ml2671 in may 1991 further tem surveys were made and a formal option signed in october 1991 in late october 1991 the first hole was drilled and this intersected strong mineralisation after further drilling the discovery of the ernest henry deposit was announced and savage exploration were advi

sed in june 1992 that the joint venture wished to exercise its option and buy the lease of ml2671 savage exploration then commenced court proceedings alleging western mining had misrepresented the situation when agreeing an option on ml2671 and that western mining had trespassed on ml2671 during the ground surveys in the ensuing court case it transpired that the pegs for ml2671 were not in the place indicated on the mines dept files and were 850 m north of the stated location and the lease was rotated several degrees anticlockwise from its plotted position the case was settled out of court with western mining agreeing to give up any claim to ml2671 and paying hunter a17 million and certain legal costs 4 3 sustainable development one of the major changes in exploration in the last 10 years has been the difficulty in obtaining a permit to develop a new mine as discussed in section 1 5 2 much research has been undertaken on the socioeconomic aspects of opening and operating a new mine see section 11 2 7 the major components of sustainable development in addition to the technical and economic components are i environmental ii social iii governmental most major companies issue annual reports on their progress in regard to these three aspects of their operations and these are available on their websites these form a good place to delve more deeply into specific examples and policies in different countries environmental aspects obtaining an environmental permit to operate a mine has become a vital part of the feasibility process but also needs to be addressed during the exploration phases obtaining a permit involves the preparation of an environmental impact statement eis describing the problems that mining will cause and the rehabilitation program that will be followed once mining is complete hinde 1993 such an impact statement requires that the condition of the environment in the potential mining area before development began is recorded a baseline survey thus it is essential to collect data during the exploration stage for use in these eiss initial data might include surface descriptions and photographs and geochemical analyses indicating background levels of metals and acidity as well as water levels and flows it is of course essential to minimize damage during exploration and to set a high standard for environmental management during any exploitation trenches and pits should be filled and any damage by tracked vehicles should be minimized and if possible made good it may be that a more expensive method of access e g helicopter supported drilling may be necessary to minimize impact during exploration checklists for various exploration activities and discussion of best practices are available at the e3 website e3 2004 data collection and baseline surveys become more intense as a prospect becomes more advanced and the prospect of an eis looms another aspect of environmental studies is public relations partic

ularly keeping the local population informed of progress and obtaining their active approval for any development project the past few years are littered with examples of projects that are technically excellent but have failed to obtain permission for development and others that have been significantly delayed causing them to become economically unviable it is at the exploration stage that the local population form impressions of the nature of the exploration group and whether they wish to be involved in its activities establishing good relation and communications with the local community is the first step in gaining their backing for future mining a social license to operate mmsd 2002 a good summary of the problems is freely available from the pdac website e3 2004 initial concerns of the local community are the transient nature of exploration and the lack of knowledge of the local population to the techniques used and their scale in addition the local population may have economic expectations and the arrival of exploration from another part of or from outside the country may cause cultural stress it is always advisable to obtain local advice for example in australia sacred aboriginal sites will be known to the local population but not to most geologists their unintentional desecration has caused the development of intense opposition to further exploration the initial contact with the local population should be carefully planned and if possible be enabled by an intermediary such as a local official trusted by both parties and probably after consulting someone with well developed skills in dealing with local government and community leaders in the area the process of exploration and possible outcomes should be carefully explained so that unrealistic expectations are not raised local labor and purchasing should be used wherever possible and training should be provided major mining companies are now aware of the problems and provide training for their field geologists emphasizing the importance of contacts with local communities in the exploration process governmental aspects relations with governments can be problematic particularly with major projects that will generate a large part of a developing country s export earnings if large amounts of money are involved in countries where public servants are poorly paid there is a tendency for significant amounts to be appropriated either in the form of taxes that do not reach the government treasury or bribes governmental relations need to be handled carefully at a senior level and care should be taken that they are not in conflict with relations at a community level see sections 11 2 6 11 2 8 there are a number of recent 2004 examples such as the esquel gold deposit in argentina where the national government is keen on the development but local or provincial bodies are opposed 4 3 1 health and safety a key aspect of a company s reputation both as an employer

and with the local community is the health and safety of its staff although problems at the exploration stage are less severe than during mining serious injuries and deaths have occurred assessments of hazards should be made so that high risk activities can be recognized and mitigated first aid training should also be provided at least one major mining group has linked staff pay to safety record and claim that this is the only way to effectively improve their safety record all contractors should behave in a similar way to company staff and safety record should be a significant factor in choosing contractors probably the major source of serious accidents in the authors experiences is road transport especially in remote areas staff should be provided with training in driving on poor road surfaces 4 4 summary mineral exploration is conducted by both the private and public sectors in both market and most centrally planned economies groups from both sectors must be clear about what commodity and type of deposit they are seeking before setting up an exploration organization mineral exploration is a long term commitment and there must be careful planning of the participant s long term objectives to ensure viable budgeting with the objective decided upon an exploration organization must be set up and its success will be enhanced by developing all the factors listed in section 4 1 1 budgets must be carefully evaluated and not be figures drawn out of the blue an underfunded project will in most cases be a failure careful control of funds is essential and it provides a basis for future budgeting with the organization in place and the target deposit type selected desk studies can start in earnest and areas for reconnaissance be chosen relevant information must be acquired assessed and selected using published works and open file material from government institutions section 4 2 1 the aim of reconnaissance is to evaluate rapidly areas highlighted in the desk study and to identify targets for follow up work and drilling if this is successful then the exclusive rights to explore and to mine any deposits found in the target area must be acquired once land has been acquired the geologist must direct his or her efforts to proving whether or not a mineral prospect is worthy of commercial evaluation proving a discovery to be of sufficient size and quality inevitably involves a subsurface investigation and the geologist usually faces the task of generating a target for drilling in exceptional cases such as very shallow mineralisation a resource may be proved by digging pits or trenches or in mountainous areas by driving adits into the mountainside whatever the method used the key requirement is to explore the area at the lowest cost without missing significant targets fulfilling this requirement is not easy and the mineral deposit models such as those discussed in chapter 3 must be modified to include economic considerations the

re should be a clear idea of the size of the deposit sought the maximum depth of interest and whether underground mining is acceptable finding a drilling target normally involves the commissioning of a number of different surveys such as a geophysical survey to locate the target and indicate its probable subsurface extension the role of the geologist and the exploration management is to decide which are necessary and to integrate the surveys to maximum effect once land has been acquired an organization and budget must be set up to explore it and bring the exploration to a successful conclusion the scale and speed of exploration will depend on the land acquisition agreements see section 4 2 3 and the overall budget if a purchase decision is required in 3 years then the budget and organization must be geared to this usually the exploration of a particular piece of land is given project status and allocated a separate budget under the responsibility of a geologist normally called the project geologist this geologist is then allocated a support team and he or she proceeds to plan the various surveys usually in collaboration with in house experts and reports his or her recommendations to the exploration management typically reporting of progress is carried out in monthly reports by all staff and in 6 monthly reviews of progress with senior exploration management these reviews are often also oral presentations show and tell sessions and linked to budget proposals for the next financial period reconnaissance projects are normally directed from an existing exploration office but once a project has been established serious consideration should be given in inhabited areas to setting up an office nearer the project location initially this may be an abandoned farmhouse or caravan but for large projects it will be a formal office in the nearest town with good communications and supplies a small office of this type is becoming much easier to organize following the improvement of communication and computing facilities during the last decade exploration data can be transferred by modem fax and satellite communications to even the remotest location if the project grows into one with a major drilling commitment then it is probable that married staff will work more effectively if their families are moved to this town in general the town should be less than 1 hour s commuting time so that a visit to a drilling rig is not a chore in the remotest areas staff will be housed in field camps and will commute by air to their home base if possible exploration staff should not be expected to stay for long periods in field camps as this is bad for morale and efficiency declines budgeting for the project is more detailed than at the reconnaissance stage and will take account of the more expensive aspects of exploration notably drilling a typical budget sheet is shown in table 4 2 usually the major expenditure will be on labor and on

the various surveys if the area is remote then transport costs particularly helicopter charter can become significant labor costs are normally calculated on the basis of man months allocated and should include an overhead component to cover office rental secretarial and drafting support commonly overheads equal salary costs for geophysical and sometimes geochemical surveys contractors are often hired as their costs can be accurately estimated and companies are not then faced with the possibility of having to generate work for staff estimates are normally made on the basis of cost per linekilometer or sample in remote areas careful consideration should be given to contractor availability the accurate location of exploration surveys relative to each other is of crucial importance and requires that the explorationist knows the basics of topographical surveying the effort put into the survey varies with the success and importance of the project at an early stage in a remote area a rough survey with the accuracy of a few meters will be adequate this can be achieved using aerial photographs and handheld global positioning satellite gps receivers ritchie et al 1977 sabins 1987 where only a few survey points are needed for a major drilling program surveying to a few millimeters will be required for accurate borehole location the usual practice when starting work on a prospect is to define a local grid for the prospect using gps to relate the local grid to the national or international grid systems see section 9 1 7 some convenient point such as a wind pump or large rock is normally taken as the origin the orientation of the grid will be parallel to the regional strike if steeply dipping mineralisation is suspected from geophysics but otherwise should be n s or e w geologists generally use simple and cheap techniques in contrast to those used by professional surveyors surveying has recently been transformed by the advent of gps based on a network of satellites installed by the us department of defense these enable a fix of approximately 5 m accuracy to be made anywhere on earth with an inexpensive currently approximately us200 receiver where three satellites can be viewed the major problems are in forested areas one of the simplest and most widely used techniques before the advent of gps is the tape and compass survey this type of survey starts from a fixed point with directions measured with a prismatic or brunton compass and distances measured with a tape or chain closed traverses i e traverses returning to the initial point are often used to minimize the errors in this method errors of distance and orientation may be distributed through the traverse section 5 1 4 grids are often laid out using this technique with baselines measured along a compass bearing distances are best measured with a chain which is less vulnerable to wear and more accurate than a tape longer baselines in flat country can be mea

sured using a bicycle wheel with a cyclometer attached lightweight hip mounted chains are commonly used in remote areas straight grid lines are usually best laid out on flat ground by back and forward sighting along lines of pegs or sticks sturdy wood or metal pegs should be used the grid locations marked with metallic tags and flagged with colored tape the tape should be animal proof goats have a particular fondness for colored tape leveling is the most accurate method of obtaining height differences between stations and is used for example to obtain the elevation of each station when undertaking gravity surveys this method measures the height difference between a pair of stations using a surveyor s level leveling is required in an underground mine to determine the minimum slope required to drain an adit or drive and in a surface mine the maximum gradient up which load haul dump lhd trucks can climb when fully laden usually 10 more exact ground surveys use a theodolite as a substitute for a compass it is simple enough for geologists to learn to use numerical triangulation is carried out using angles measured by theodolite to calculate x and y coordinates by also recording the vertical angles the heights of points can be computed ritchie et al 1977 professional surveyors are readily available in most parts of the world and they should be contracted for more exact surveys they will use a theodolite and electronic distance measuring edm equipment often combined in one instrument and can produce an immediate printout of the grid location of points measured one of the key elements during the exploration of a prospect is the preparation of a geological map its quality and scale will vary with the importance of the program and the finance available initial investigation of a prospect may only require sketch mapping on an aerial photograph whereas detailed investigations prior to drilling may necessitate mapping every exposure mapping at the prospect scale is generally undertaken at 1 10 000 to 1 2500 for detailed accurate mapping a telescopic alidade and plane table or differential gps may be used the principle of the alidade is the same as for a theodolite except that the vertical and horizontal distances between each point are calculated in the field the base of the alidade is used to plot the position of the next point on the waterproof drafting film covering the plane table the process of geological mapping of mineral prospects is similar to that of general geological mapping but is more focused and is well described in the book by majoribanks 1997 although the regional environment of the prospect is important particular attention will fall on known mineralisation or any discovered during the survey the geological relationship of the mineralisation must be assessed in detail in particular whether it has any of the features of the geological model sought for example if the target is a volcanic asso

ciated massive sulfide deposit then any sulfides should be carefully mapped to determine if they are concordant or cross cutting if the sulfides are cross cutting it should be established whether the sulfides are in a stockwork or a vein particular attention should be paid to mapping hydrothermal alteration which is described in detail by pirajno 1992 detailed guidance on geological mapping is beyond the scope of this book but can be found in a series of handbooks published by the geological society of london fry 1991 mcclay 1991 thorpe brown 1993 tucker 2003 particularly in the summary volume of barnes and lisle 2003 one of the key elements of mapping is its final presentation conventionally this was in the form of a map drafted by indian ink pen on to transparent film from film multiple copies either on film or on paper can be made using the dyeline process and the map can be overlaid on other maps of the same scale allowing easy comparison of features and selection of targets the conventional pen and paper approach has been superseded by computerized drafting that allows the storage of information in digital form computer packages such as autocad a computer aided drafting package are widely used in industry see section 9 2 maps and plans can be produced to scale and different features of the overall data set held on different layers in the computer can be selected for viewing on the computer screen or printed as a hard copy the data can also be transmitted to more sophisticated geographical information systems gis for example arcgis or mapinfo that allow the inquisition of data see section 9 2 5 1 4 mapping and sampling of old mines many prospects contain or are based around old mines they may become attractive as exploration targets because of rising commodity prices cheaper mining and processing costs the development of new technology which may improve recovery or the development of a new geological model which could lead to undiscovered mineralisation the presence of a mining district indicates mineral potential which must reduce the exploration risk however there will be a premium to pay as the property will probably already be under option to or owned by a rival company the type of examination warranted by an old mine will depend on its antiquity size and known history in europe and west asia old mines may be over 2000 years in age and be the result of roman or earlier activity in this case there are few if any records and the target commodity can only be guessed at in such cases small areas of disturbed ground indicating the presence of old prospecting pits or trenches can best be found from aerial photography field checking and grab sampling will confirm the presence and indicate the possible type of mineralisation nineteenth or twentieth century mines are likely to be larger and have more extensive records available records should be obtained but should be treated with some

caution as many reports are unreliable and plans likely to be incomplete an aim of this type of investigation is to check any records carefully by using systematic underground sampling above the water level as old mines are frequently flooded evaluation of extensive underground workings requires considerable planning and will be more expensive than surface exploration because equipment and labor for development and securing old underground workings are costly a key consideration is safety and access to the old workings must be made safe before any sampling program is established it may be necessary to undertake trenching and pitting in areas adjacent to the old workings and eventually drilling may be used to examine the deeper parts of the inaccessible mineralisation before a sampling program can be put into operation a map of the old workings will be required if none is available from archives the exploration geologist is often the first person at the site and it is up to him or her to produce a plan and section of the old workings this would be done using a tape and compass survey ritchie et al 1977 reedman 1979 peters 1987 majoribanks 1997 table 5 1 figs 5 1 5 2 once the layout of the old workings is known the mapping and complementary sampling program can begin the survey pegs established during the surveying will be used to locate the sample points and guide mapping with the tape held between the pegs the sample points are marked on the drive or crosscut walls and the distance from one peg to the sample point recorded in the field note book along with the sample number the same number is written on a sample ticket and included with the sample in the sample bag the samples are normally collected at regular intervals from channels cut normal to the dip of the mineralized rock fig 5 3 the sample interval varies depending upon the type of mineralisation a vein gold deposit may well be sampled at 1 m intervals along every drive while a copper deposit may only be sampled every 5 or 10 m if old records are available and reliable then their data should be evaluated in conjunction with new sample data acquired during the remapping and resampling exercises geological controls on mineralisation should be established using isopach and structure contour maps as discussed in section 5 2 2 it may be necessary to apply a cut off value below which the mineralisation is not considered mineable in table 5 2 two cut off parameters lane 1988 are used in one a direct cut off and in the second a weighted average value is used in the first case the upper sample cut off is taken where the individual grade falls below 1 5 some assays within this sample are also below 1 5 but they are surrounded by higher values which when averaged out locally have a mean greater than 1 5 the samples between the two lines are then averaged using the sample thickness as the weighting function giving an average of 2 26 zn over 2 1

0 m in the second case the samples are averaged from the base upwards using thickness as the weighting function the weighted average is calculated until the average falls above the cutoff which in this case makes 1 59 zn over 3 40 m the inclusion of just one more sample would bring the average down below 1 5 the overall weighted average is 1 35 zn over 4 00 m once the samples have been collected bagged and labeled they must be sent to the laboratory for analysis not only must the elements of interest be specified but the type of analytical procedure should be discussed with the laboratory cost should not be the overriding factor when choosing a laboratory accuracy precision and an efficient procedure are also needed an efficient procedure within one s own office is also required sample numbers and the analyses requested should be noted down rigorously on a sample control form box 5 1 an alternative practice is to state clearly the instructions for test work on the sample sheet box 5 2 in coal analytical work there are several ways in which the proximate analyses moisture volatile ash and fixed carbon contents can be reported e g on an as received moisture free or dry ash free basis stach 1982 speight 1983 ward 1984 thomas 1992 a similar form may well be utilized for sand and gravel or crushed rock analyses where the geologist requires special test work on his or her samples such as size analysis aggregate crushing value acv or polished stone value psv to name but a few in today s computerized era results are often returned to the company either on a floppy disk or direct to the company s computer from the laboratory s computer via a modem and a telephone link care must be taken when entering the results thus obtained into the company s database that the columns of data in the laboratory s results correspond with the columns in your own data base discussed in detail in section 9 1 gold values of several percent and copper values in the ppb range should alert even the most unsuspecting operator to an error before samples are submitted to the laboratory discussions between the project manager chief geologist and the field staff should take place to ensure that all the elements that may be associated with the mineral deposit in question are included on the analytical request sheet and that analysis includes possible pathfinder elements typical elemental associations are discussed in detail in chapter 8 analytical techniques there are a wide variety of analytical techniques available to the exploration geologist the method selected depends upon the element which is being analysed and upon the amount expected amongst the instumental methods available are atomic absorption spectrometry aas x ray fluorescence xrf x ray diffraction xrd neutron activation analysis naa and inductively coupled plasma emission or mass spectrometry icpes ms aas is a relatively inexpensive method of

analysis and some exploration camps now have an instrument in the field this ensures rapid analysis of the samples for immediate follow up the other methods involve purchasing expensive equipment and this is usually left to specialist commercial laboratories detailed identification of individual minerals is usually undertaken using a scanning electron microscope sem or an electron microprobe one of the key exploration activities is the location of surface mineralisation and any old workings although this often results from the follow up of geochemical and geophysical anomalies or is part of routine geological mapping it can also be the province of less formally trained persons these prospectors compensate for their lack of formal training with a detailed knowledge of the countryside and an acute eye an eye for ore this eye for ore is the result of experience of the recognition of weathered outcrops and the use of a number of simple field tests many deposits which crop out have been recognized because they have a very different appearance from the surrounding rocks and form distinct hills or depressions besides forming topographical features most outcropping mineral deposits have a characteristic color anomaly at the surface the most common of these is the development of a red yellow or black color over iron rich rocks particularly those containing sulfides these altered iron rich rocks are known generically as ironstones and iron oxides overlying metallic sulfide deposits as gossans or iron hats an example is shown in fig 5 4 these relic ironstones can be found in most areas of the world with the exception of alpine mountains and polar regions and result from the instability of iron sulfides particularly pyrite weathering releases so4 2 ions leaving relic red iron oxides hematite or yellow brown oxyhydroxides limonite that are easily recognized in the field other metallic sulfides weather to form even more distinctively colored oxides or secondary minerals for example copper sulfides oxidize to secondary minerals that have distinctive green or blue colors such as malachite and azurite metals such as lead and zinc normally form white secondary minerals in carbonate areas that are not easily distinguished on color grounds from the host carbonates a fuller list is given in table 5 3 besides providing ions to form secondary minerals sulfides often leave recognizable traces of their presence in the form of the spaces that they occupied these spaces are relic textures often known as boxworks from their distinctive shapes and are frequently infilled with limonite and goethite ironstones overlying sulfides have a varied appearance with much alternation of color and texture giving rise to the term live in contrast to ironstones of nonsulfide origin that show little variation and are known as dead ironstones ironstones also preserve chemical characteristics of their parent rock although these can be con

siderably modified due to the leaching of mobile elements the recognition of weathered sulfides overlying base metal or gold deposits and the prediction of subsurface grade is therefore of extreme importance this particularly applies in areas of laterite development these areas such as much of western australia have been stable for long periods of geological time all rocks are deeply weathered and the percentage of ironstones that overlie nonbase metal sulfides known rather loosely as false gossans is large in western australia the main techniques for investigating these are butt zeegers 1992 1 visual description of weathered rocks 2 examination for relic textures 3 chemical analysis visual recognition requires experience and a good knowledge of primary rock textures visual recognition can also be supplemented by chemical analysis for trace and major elements hallberg 1984 showed that zr tio2 plots are extremely useful in confirming rock types both elements are immobile and easy and cheap to determine at the levels required they may be supplemented by cr determinations in ultrabasic areas although cr is more mobile than the other two elements relic textures can sometimes be observed in hand specimen but this is usually supplemented by microscopic examination using either a binocular microscope or a petrographic microscope and an impregnated thin section in a classic study of relic textures blanchard 1968 described the textures resulting from the weathering of sulfides major types are shown in fig 5 5 although boxwork textures are diagnostic they are unfortunately not present in every gossan overlying base metal sulfides and textural examination must be supplemented by chemical analysis the choice of material to be sampled and the interpretation need to be carefully scrutinized andrew 1978 recommends taking 20 samples as representative of each gossan and using a multielement analysis either xrf or icp es following a total attack to dissolve silica the interpretation needs to be treated with care a large amount of money was wasted in western australia at the height of the nickel boom in the early 1970s because ironstones were evaluated for potential on the basis of their nickel content while most ironstones with very high nickel contents do overlie nickel sulfide deposits a number have scavenged the relatively mobile nickel from circulating ground waters or overlie silicate sources of nickel and a number of deposits have a weak nickel expression at surface more careful research demonstrated that it is better to consider the ratio of nickel to more immobile elements such as copper or even better immobile iridium that is present at the sub ppm level in the deposits these elements can be combined into a discriminant index travis et al 1976 moeskops 1977 similar considerations also apply to base metal deposits barium and lead have been shown to be useful immobile tracers in these summarized in but

t zeegers 1992 field tests although a large number of field tests have been proposed in the literature only a few of the simplest are in routine use at present only two geophysical instruments can be routinely carried by man a scintillometer to detect gamma radiation and a magnetic susceptibility meter to determine rock type 5 ultraviolet lamps to detect fluorescence of minerals at night are commonly used particularly for scheelite detection although a number of other minerals glow chaussier morer 1987 in more detailed prospecting darkness can be created using a tarpaulin a number of simple field chemical tests aid in the recognition of metal enrichments in the field usually by staining particularly useful tests aid the recognition of secondary lead and zinc minerals in carbonate areas lead minerals can be identified in outcrops by reaction with potassium iodide following acidification with hydrochloric acid lead minerals form a bright yellow lead iodide a bright red precipitate results when zinc reacts with potassium ferrocyanide in oxalic acid with diethylaniline gray copper minerals can be detected with an acidified mixture of ammonium pyrophosphate and molybdate and nickel sulfides with dimethyl glyoxine as metallic ions are leached at the surface they are moved in solution and deposited at changes in environmental conditions usually at the water table where active oxidation and generation of electrical charge takes place this leaching and deposition has very important economic implications that are particularly significant in the case of copper deposits as illustrated in fig 5 6 copper is leached from the surface leaving relic oxidized minerals concentrated at the water table in the form of secondary sulfides a simple eh ph diagram enables the prediction of the occurrence of the different copper minerals from the surface these are malachite cuprite covellite chalcocite bornite and chalcopyrite the primary phase the changes in mineralogy have important implications for the recovery of the minerals and the overall grade of the rock oxide minerals cannot be recovered by the flotation process used for sulfides and their recovery needs a separate circuit the overall grade of the surface rock is much lower than the primary ore and sampling of the surface outcrops does not reflect that of the primary ore near the water table the copper grade increases as the result of the conversion of chalcopyrite 35 cu to chalcocite 80 cu this enrichment known as supergene enrichment often provides high grade zones in disseminated copper deposits such as those of the porphyry type these high grade zones provide much extra revenue and may even be the basis of mines with low primary grades in contrast to the behavior of copper gold is less mobile and is usually concentrated in oxide zones if these oxide zones represent a significant amount of leaching over a long period then the gold grades may be become econ

omic these near surface high grade zones are especially important as they provide high revenue during the early years of a mine and the opportunity to repay loans at an early stage these gold rich gossans can also be mechanically transported for considerable distances the skill of tracing mineralized boulders or rock fragments is extremely valuable in areas of poor exposure or in mountainous areas in mountainous areas the rock fragments have moved downslope under gravity and the lithology hosting the mineralisation can be matched with a probable source in a nearby cliff and a climb attempted float mapping and sampling is often combined with stream sediment sampling and a number of successful surveys have been reported from papua new guinea lindley 1987 in lowland areas mineralized boulders are often disturbed during cultivation and may be moved to nearby walls in this case it is often difficult to establish a source for the boulders and a soil survey and a subsequent trench may be necessary burrowing animals may also be of help moles or rabbits and termites in tropical areas often bring small fragments to the surface in glaciated areas boulders may be moved up to tens of kilometers and distinct boulder trains can be mapped in areas of poor to moderate outcrop a trench fig 5 8 or pit is invaluable in confirming the bedrock source of an anomaly be it geological geochemical or geophysical the geology of a trench or pit wall should be described and illustrated in detail fig 5 9 for further details see section 9 2 trenches and pits also provide large samples for more accurate grade estimates as well as for undertaking pilot processing plant test work to determine likely recoveries some operators in remote areas particularly in central canada strip relatively large areas of the overburden to enable systematic mapping of bedrock however this would now probably be regarded as environmentally unfriendly an alternative to disturbing the environment by trenching is to use a hand held drill for shallow drilling this type of drill is lightweight and can be transported by two people it produces a small core usually around 25 30 mm in diameter penetration is usually limited but varies from around 5 m to as much as 45 m depending on the rig rock type and skill of the operators geophysical and geochemical surveys can indicate the surface or subsurface geology of the potential host rocks or more directly the presence of mineralisation traditionally the results of these surveys have been combined by overlaying colored transparent copies of the data on a topographical or geological paper base it is then possible to determine the interrelation between the various data sets more recent developments have allowed the use of computerized methods gis which allow rapid integration and interrogation of the databases one of the hardest decisions in exploration is to decide when to start drilling and an even harder one is w

hen to stop the pressure to drill will be evident when the program has identified surface mineralisation management will naturally be keen to test this and gain an idea of subsurface mineralisation as soon as possible however this pressure should be resisted until there is a reasonable idea of the overall surface geology and the inferences that can be made from this knowledge concerning mineralisation in depth the geologist in charge of a drilling program is faced with a number of problems both logistical and geological there must be a decision on the type of drilling required the drillhole spacing see section 10 4 4 the timing of drilling and the contractor to be used the logistics of drilling should be considered carefully as the drill will need drill crews consumables and spare parts this will require helicopter support in remote areas and vehicle access in more populated areas many drills require vehicle access and access roads must be made and pads for drilling constructed so that the drill rigs can be set on an almost horizontal surface the pattern of drilling used is dependent on the assumed attitude and thickness of the drilling target this depends on the available information which may of course be inaccurate drilling often causes reconsideration of geological ideas and prejudices vertical boreholes are the easiest and cheapest to drill and widely used for mineralisation with a shallow dip or for disseminated deposits however inclined holes are usually preferred for targets with steep dips the aim will be to cut the mineralisation at 90 degrees with the initial hole cutting immediately below the zone of oxidation weathered zone fig 5 11 drilling is used to define the outlines of any deposit and also the continuity of mineralisation for purposes of resource estimation the initial pattern of drilling will depend on surface access which may be very limited in mountainous areas in areas without access problems typical drill hole patterns are square with a regular pattern or with rows of holes offset from adjacent holes the first hole normally aimed at the down dip projection of surface anomalies or the interpreted centre of subsurface geophysics most programs are planned on the basis of a few test holes per target with a review of results while drilling the spacing between holes will be based on anticipated target size previous company experience with deposits of a similar type and any information on previous competitor drilling in the district whateley 1992 the subsequent drilling location and orientation of the second and third holes will depend on the success of the first hole success will prompt step outs from the first hole whereas a barren and geologically uninteresting first hole will suggest that another target should be tested once a deposit has been at least partly defined then the continuity of mineralisation must be assessed the spacing between holes depends on the type of mineralis

ation and its anticipated continuity in an extreme case e g some vein deposits boreholes are mainly of use in indicating structure and not much use in defining grade which can only be accurately determined by underground sampling see chapter 10 typical borehole spacing for a vein deposit is 25 50 m and for stratiform deposits anything from 100 m to several hundreds of meters monitoring the geology and mineralisation intersected during a drilling program is vital in controlling costs in the initial phases of drilling this may involve the geologist staying beside the rig if it is making rapid progress e g when using percussion drilling and logging material as it comes out of the drill hole in the case of diamond drilling twice daily visits to examine core make initial logs and decide on the location of the next drill holes are usually sufficient although longer visits will be needed when cutting potentially mineralized zones or nearing the scheduled end of the hole often the geologist will be required by contractors to sign for progress or the use of casing besides detailed core logs down hole geophysical logging see section 7 14 is often used and arrangements should be made with contractors for timely logging as holes can become rapidly blocked and cleaning of holes is an expensive undertaking data on mineralisation the lithologies and structures hosting it should be recorded and plotted on to a graphic log as soon as the information becomes available initially strip drill logs fig 5 13 can be used and sections incorporating the known surface geology assay information will usually be delayed for a few days as the cores will need to be split or cut and sampled before analysis see chapter 10 however estimates of the location and importance of mineralisation can be plotted alongside the lithological log fig 5 15e as further drilling proceeds the structural and stratigraphical controls on mineralisation should become clearer ambiguities concerned with the interpretation of drilling are common and often cannot be resolved until there has been underground development a typical example is shown in fig 5 14 in which three different interpretations are possible from the information available once a stratigraphy has been established and several boreholes are available more sophisticated plotting techniques can be used typical methods used to plot drillhole information are structure contour plans isopach grade quality thickness and grade multiplied by thickness known as the grade thickness product or accumulation maps grade and grade thickness product maps are extremely useful in helping to decide on the areal location of oreshoots and of helping direct drilling towards these shoots fig 5 15 pp 91 92 one of the key issues in any drilling program is continuity of mineralisation this determines the spacing of drill holes and the accuracy of any resource estimation as discussed in chapter 10 in mo