Economic geology

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An open pit uranium mine in Namibia Arandis Mine quer.jpg
An open pit uranium mine in Namibia

Economic geology is concerned with earth materials that can be used for economic and/or industrial purposes. These materials include precious and base metals, nonmetallic minerals, construction-grade stone, petroleum, natural gas, coal, and water. Economic geology is a subdiscipline of the geosciences; according to Lindgren (1933) it is “the application of geology”. Today, it may be called the scientific study of the Earth's sources of mineral raw materials and the practical application of the acquired knowledge. [1] The term commonly refers to metallic mineral deposits and mineral resources. The techniques employed by other earth science disciplines (such as geochemistry, mineralogy, geophysics, petrology and structural geology) might all be used to understand, describe, and exploit an ore deposit.

A base metal is a common and inexpensive metal, as opposed to a precious metal such as gold or silver. A long-time goal of alchemists was the transmutation of a base metal into a precious metal. In numismatics, coins often derived their value from the precious metal content; however, base metals have also been used in coins in the past and today.

Dimension stone Natural stone that has been finished to specific sizes and shapes

Dimension stone is natural stone or rock that has been selected and finished to specific sizes or shapes. Color, texture and pattern, and surface finish of the stone are also normal requirements. Another important selection criterion is durability: the time measure of the ability of dimension stone to endure and to maintain its essential and distinctive characteristics of strength, resistance to decay, and appearance.

Petroleum naturally occurring flammable liquid

Petroleum is a naturally occurring, yellowish-black liquid found in geological formations beneath the Earth's surface. It is commonly refined into various types of fuels. Components of petroleum are separated using a technique called fractional distillation, i.e. separation of a liquid mixture into fractions differing in boiling point by means of distillation, typically using a fractionating column.

Contents

Economic geology is studied and practiced by geologists. Economic geology may be of interest to other professions such as engineers, environmental scientists, and conservationists because of the far-reaching impact that extractive industries have on society, the economy, and the environment.

Purpose of studies

The purpose of the study of economic geology is to gain understanding of the genesis and localization of ore deposits plus the minerals associated with ore deposits. [2] Though metals, minerals and other geologic commodities are non-renewable in human time frames, the impression of a fixed or limited stock paradigm of scarcity has always led to human innovation resulting in a replacement commodity substituted for those commodities which become too expensive. Additionally the fixed stock of most mineral commodities is huge (e.g., copper within the earth's crust given current rates of consumption would last for more than 100 million years. [3] Nonetheless, economic geologists continue to successfully expand and define known mineral resources.

Ore genesis How the various types of mineral deposits form within the Earths crust.

Various theories of ore genesis explain how the various types of mineral deposits form within the Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.

Prospectivity mapping, also known as mineral prospectivity mapping or mineral potential mapping, defines a process used to make better use of mineral exploration data. Geological and geophysical datasets, such as lithological, structural and topographical maps, aeromagnetic, gravity and radiometric imagery are the typical datasets used in the construction of prospectivity maps.

Mineral resources

Mineral resources are concentrations of minerals significant for current and future societal needs. Ore is classified as mineralization economically and technically feasible for extraction. Not all mineralization meets these criteria for various reasons. The specific categories of mineralization in an economic sense are:

Ore geology

Citrobacter species can have concentrations of uranium in their bodies 300 times higher than in the surrounding environment. Citrobacter freundii.jpg
Citrobacter species can have concentrations of uranium in their bodies 300 times higher than in the surrounding environment.

Geologists are involved in the study of ore deposits, which includes the study of ore genesis and the processes within the Earth's crust that form and concentrate ore minerals into economically viable quantities.

Study of metallic ore deposits involves the use of structural geology, geochemistry, the study of metamorphism and its processes, as well as understanding metasomatism and other processes related to ore genesis.

Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation (strain) in the rocks, and ultimately, to understand the stress field that resulted in the observed strain and geometries. This understanding of the dynamics of the stress field can be linked to important events in the geologic past; a common goal is to understand the structural evolution of a particular area with respect to regionally widespread patterns of rock deformation due to plate tectonics.

Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the entire Solar System, and has made important contributions to the understanding of a number of processes including mantle convection, the formation of planets and the origins of granite and basalt.

Metamorphism The change of minerals in pre-existing rocks without melting into liquid magma

Metamorphism is the change of minerals or geologic texture in pre-existing rocks (protoliths), without the protolith melting into liquid magma. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. The chemical components and crystal structures of the minerals making up the rock may change even though the rock remains a solid. Changes at or just beneath Earth's surface due to weathering or diagenesis are not classified as metamorphism. Metamorphism typically occurs between diagenesis, and melting (~850°C).

Ore deposits are delineated by mineral exploration, which uses geochemical prospecting, drilling and resource estimation via geostatistics to quantify economic ore bodies. The ultimate aim of this process is mining.

Boring (earth) drilling a hole, tunnel, or well in the earth; used for a various applications in geology, agriculture, hydrology, civil engineering, and mineral exploration

Boring is drilling a hole, tunnel, or well in the earth.

Geostatistics is a branch of statistics focusing on spatial or spatiotemporal datasets. Developed originally to predict probability distributions of ore grades for mining operations, it is currently applied in diverse disciplines including petroleum geology, hydrogeology, hydrology, meteorology, oceanography, geochemistry, geometallurgy, geography, forestry, environmental control, landscape ecology, soil science, and agriculture. Geostatistics is applied in varied branches of geography, particularly those involving the spread of diseases (epidemiology), the practice of commerce and military planning (logistics), and the development of efficient spatial networks. Geostatistical algorithms are incorporated in many places, including geographic information systems (GIS) and the R statistical environment.

Mining The extraction of valuable minerals or other geological materials from the earth

Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef or placer deposit. These deposits form a mineralized package that is of economic interest to the miner.

Coal and petroleum geology

Mud log in process, a common way to study the lithology when drilling oil wells. Mudlogging.JPG
Mud log in process, a common way to study the lithology when drilling oil wells.
See main articles Coal and Petroleum geology

The study of sedimentology is of prime importance to the delineation of economic reserves of petroleum and coal energy resources.

Sedimentology encompasses the study of modern sediments such as sand, silt, and clay, and the processes that result in their formation, transport, deposition and diagenesis. Sedimentologists apply their understanding of modern processes to interpret geologic history through observations of sedimentary rocks and sedimentary structures.

Coal A combustible sedimentary rock composed primarily of carbon

Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements; chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed if dead plant matter decays into peat and over millions of years the heat and pressure of deep burial converts the peat into coal. Vast deposits of coal originates in former wetlands—called coal forests—that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times.

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Related Research Articles

Skarn Hard, coarse-grained, hydrothermally altered metamorphic rocks

Skarns or tactites are hard, coarse-grained metamorphic rocks that form by a process called metasomatism. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate minerals. These minerals form as a result of alteration which occurs when hydrothermal fluids interact with a protolith of either igneous or sedimentary origin. In many cases, skarns are associated with the intrusion of a granitic pluton found in and around faults or Shear zones that intrude into a carbonate layer composed of either dolomite or limestone. Skarns can form by regional, or contact metamorphism and therefore form in relatively high temperature environments. The hydrothermal fluids associated with the metasomatic processes can originate from either magmatic, metamorphic, meteoric, marine, or even a mix of these. The resulting skarn may consist of a variety of different minerals which are highly dependent on the original composition of both the hydrothermal fluid and the original composition of the protolith.

Mining engineering engineering discipline that involves the practice, the theory, the science, the technology, and applicatIon of extracting and processing minerals from a naturally occurring environment

Mining engineering is an engineering discipline that applies science and technology to the extraction of minerals from the earth. Mining engineering is associated with many other disciplines, such as mineral processing, Exploration, Excavation, geology, and metallurgy, geotechnical engineering and surveying. A mining engineer may manage any phase of mining operations – from exploration and discovery of the mineral resource, through feasibility study, mine design, development of plans, production and operations to mine closure.

Exploration geophysics is an applied branch of geophysics and economic geology, which uses physical methods, such as seismic, gravitational, magnetic, electrical and electromagnetic at the surface of the Earth to measure the physical properties of the subsurface, along with the anomalies in those properties. It is most often used to detect or infer the presence and position of economically useful geological deposits, such as ore minerals; fossil fuels and other hydrocarbons; geothermal reservoirs; and groundwater reservoirs.

Mineral resource classification

Mineral resource classification is the classification of mineral resources based on an increasing level of geological knowledge and confidence. Mineral deposits can be classified as:

Waldemar Lindgren American geologist

Waldemar Lindgren was a Swedish-American geologist. Lindgren was one of the founders of modern economic geology.

National Instrument 43-101 is a national instrument for the Standards of Disclosure for Mineral Projects within Canada. The Instrument is a codified set of rules and guidelines for reporting and displaying information related to mineral properties owned by, or explored by, companies which report these results on stock exchanges within Canada. This includes foreign-owned mining entities who trade on stock exchanges overseen by the Canadian Securities Administrators, even if they only trade on Over The Counter (OTC) derivatives or other instrumented securities.

Uranium ore deposits are economically recoverable concentrations of uranium within the Earth's crust. Uranium is one of the more common elements in the Earth's crust, being 40 times more common than silver and 500 times more common than gold. It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors.

The following outline is provided as an overview of and topical guide to geology:

Mining in Afghanistan is controlled by the Ministry of Mines and Petroleum, which is headquartered in Kabul with regional offices in other parts of the country. Afghanistan has over 1,400 mineral fields, containing barite, chromite, coal, copper, gold, iron ore, lead, natural gas, petroleum, precious and semi-precious stones, salt, sulfur, talc, and zinc, among many other minerals. Gemstones include high-quality emerald, lapis lazuli, red garnet and ruby. According to a joint study by The Pentagon and the United States Geological Survey, Afghanistan has an estimated US$3 trillion of untapped minerals.

Natural resource economics

Natural resource economics deals with the supply, demand, and allocation of the Earth's natural resources. One main objective of natural resource economics is to better understand the role of natural resources in the economy in order to develop more sustainable methods of managing those resources to ensure their availability to future generations. Resource economists study interactions between economic and natural systems, with the goal of developing a sustainable and efficient economy.

Geologist Scientist who studies geology

A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes the Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, although backgrounds in physics, chemistry, biology, and other sciences are also useful. Field work is an important component of geology, although many subdisciplines incorporate laboratory work.

Iron oxide copper gold ore deposits (IOCG) are important and highly valuable concentrations of copper, gold and uranium ores hosted within iron oxide dominant gangue assemblages which share a common genetic origin.

Peak minerals marks the point in time when the largest production of a mineral will occur in an area, with production declining in subsequent years. While most mineral resources will not be exhausted in the near future, global extraction and production is becoming more challenging. Miners have found ways over time to extract deeper and lower grade ores with lower production costs. More than anything else, declining average ore grades are indicative of ongoing technological shifts that have enabled inclusion of more 'complex' processing – in social and environmental terms as well as economic – and structural changes in the minerals exploration industry and these have been accompanied by significant increases in identified Mineral Reserves.

Carl Michael Lesher is an American geologist. He is an authority on the geology and origin of nickel-copper-platinum group element deposits, especially those associated with komatiites, their physical volcanology and localization, the geochemistry and petrology of associated rocks, and controls on their composition.

The Mineral Exploration Research Centre (MERC) is a semi-autonomous research centre associated with the Harquail School of Earth Sciences at Laurentian University in Sudbury Ontario, Canada, and one of the largest mineral exploration research-teaching clusters in the world. MERC is housed in the Willett Green Miller Mineral and Mining Research Centre on the Laurentian University campus, together with the Ontario Geological Survey, Ontario Geoscience Laboratories, John B. Gammon Mines Library, the administrative offices of the Minerals and Mining Division of the Ontari Ministry of Northern Development and Mines, MIRARCo, and Centre for Excellence in Mining Innovation.

Mining geology is an applied science which combines the principles of economic geology and mining engineering to the development of a defined mineral resource. Mining geologists and engineers work to develop an identified ore deposit to economically extract the ore.

Resource estimation is used to determine and define the ore tonnage and grade of a geological deposit, from the developed block model. There are different estimation methods used for different scenarios dependent upon the ore boundaries, geological deposit geometry, grade variability and the amount of time and money available. A typical resource estimation involves the construction of a geological and resource model with data from various sources. Depending on the nature of the information and whether the data is hard copy or computerized, the principal steps of computer resource estimation are:

  1. Creation, standardization and validation of the database.
  2. Section plotting and interactive geological modeling.
  3. Geostatistical analysis.
  4. Block modeling and block estimation.

References

  1. Pohl, W.L., 2011. Economic Geology, Principles and Practice: Metals, Minerals, Coal and Hydrocarbons – an Introduction to Formation and Sustainable Exploitation of Mineral Deposits. 663 Pages, Wiley-Blackwell, Oxford.
  2. J. M. Gilbert and C. F. Park, Jr., 2007, The Geology of Ore Deposits, 985 pages, Waveband Press, Long Grove, IL
  3. J.E. Tilton, 2010, "Is Mineral Depletion a threat to sustainable mining?", Society of Economic Geologists Newsletter, No. 82