SEARCH · Geology Reports

Results for “Minerals and Energy - Raw Materials Report”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

USGS2011

Estimates of electricity requirements for the recovery of mineral commodities, with examples applied to sub-Saharan Africa

To produce materials from mine to market it is necessary to overcome obstacles that include the force of gravity, the strength of molecular bonds, and technological inefficiencies. These challenges are met by the application of energy to accomplish the work that includes the direct use of electricity, fossil fuel, and manual labor. The tables and analyses presented in this study contain estimates of electricity consumption for the mining and processing of ores, concentrates, intermediate products, and industrial and refined metallic commodities on a kilowatt-hour per unit basis, primarily the metric ton or troy ounce. Data contained in tables pertaining to specific currently operating facilities are static, as the amount of electricity consumed to process or produce a unit of material changes over time for a great number of reasons. Estimates were developed from diverse sources that included feasibility studies, company-produced annual and sustainability reports, conference proceedings, discussions with government and industry experts, journal articles, reference texts, and studies by nongovernmental organizations.

Open-File Report↗

USGS1985

Hydrologic and geochemical data for the Big Brown lignite mine area, Freestone County, Texas

Lignite mining in east and east-central Texas is increasing in response to increased energy needs throughout the State. Associated with the increase in mining activities is a greater need to know the effects of mining activities on the water quantity and quality of near-surface aquifers. The near-surface lignite beds mined at the Big Brown Lignite Mine are from the Calvert Bluff Formation of the Wilcox Group of Eocene age, which is a minor aquifer generally having water suitable for all uses, in eastern Freestone County, Texas. One of the potential hydro!ogic effects of surface-coal mining is a change in the quality of ground water associated with replacement of aquifer materials by mine spoils. The purpose of this report is to compile and categorize geologic, mineralogic, geochemical, and hydrologic data for the Big Brown Lignite Mine and surrounding area in east-central Texas. Included are results of pasteextract analyses, constituent concentrations in water from batch-mixing experiments, sulfur analyses, and minerals or mineral groups detected by X-ray diffraction in 12 spoil material samples collected from 3 locations at the mine site. Also, common-constituent and trace-constituent concentrations in water from eight selected wells, located updip and downdip from the mine, are presented. Dissolved-solids concentrations in water from batch-mixing experiments vary from 12 to 908 milligrams per liter. Water from selected wells contain dissolved-solids concentrations ranging from 75 to 510 milligrams per liter.

Open-File Report↗

USGS2017

Environmental considerations related to mining of nonfuel minerals

Throughout most of human history, environmental stewardship during mining has not been a priority partly because of the lack of applicable laws and regulations and partly because of ignorance about the effects that mining can have on the environment. In the United States, the National Environmental Policy Act of 1969, in conjunction with related laws, codified a more modern approach to mining, including the responsibility for environmental stewardship, and provided a framework for incorporating environmental protection into mine planning. Today, similar frameworks are in place in the other developed countries of the world, and international mining companies generally follow similar procedures wherever they work in the world. The regulatory guidance has fostered an international effort among all stakeholders to identify best practices for environmental stewardship. The modern approach to mining using best practices involves the following: (a) establishment of a pre-mining baseline from which to monitor environmental effects during mining and help establish geologically reasonable closure goals; (b) identification of environmental risks related to mining through standardized approaches; and (c) formulation of an environmental closure plan before the start of mining. A key aspect of identifying the environmental risks and mitigating those risks is understanding how the risks vary from one deposit type to another—a concept that forms the basis for geoenvironmental mineral-deposit models. Accompanying the quest for best practices is the goal of making mining sustainable into the future. Sustainable mine development is generally considered to be development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs. The concept extends beyond the availability of nonrenewable mineral commodities and includes the environmental and social effects of mine development. Global population growth, meanwhile, has decreased the percentage of inhabitable land available to support society’s material needs. Presently, the land area available to supply the mineral resources, energy resources, water, food, shelter, and waste disposal needs of all Earth’s inhabitants is estimated to be 135 square meters per person. Continued global population growth will only increase the challenges of sustainable mining. Current trends in mining are also expected to lead to new environmental challenges in the future, among which are mine-waste management issues related to mining larger deposits for lower ore grade; water-management issues related to both the mining of larger deposits and the changes in precipitation brought about by climate change; and greenhouse gas issues related to reducing the carbon footprint of larger, more energy-intensive mining operations.

Professional Paper↗

USGS1979

A proposed U.S. resource classification system

Energy is a worldwide problem calling for worldwide communication to resolve the many supply and distribution problems. Essential to a communication problem is a definition and comparability of elements being communicated. The U.S. Geological Survey, with the cooperation of the U.S. Bureau of Mines and the U.S. Department of Energy, has devised a classification system for all mineral resources, the principles of which we believe offer the possibility of world communication. At this time several other systems, extant or under development (Potential Gas Committee of the U.S., United Nations Resource Committee, and the American Society of Testing and Materials), are internally consistent and provide easy communication linkage. The system in use by the uranium community in the United States, however, ties resource quantities to Forward-Cost dollar values rendering them inconsistent with other classifications and not therefore comparable. The paper will then develop the rationale for the new USGS resource classification and note its benefits relative to a Forward-Cost classification and its relationship specifically to other extant classifications.

Open-File Report↗

USGS2003

Geochemistry of bedrock and glacial deposits in the vicinity of the Bend massive sulfide deposit, north central Wisconsin

In 1998 the U.S. Geological Survey (USGS) initiated a study to examine the natural regional environmental impact of sulfide mineralization exposed to episodic weathering and glaciation. The study focused on the Bend copper-gold massive sulfide deposit located in the Medford District of the Chequamegon National Forest in north central Wisconsin. The Bend massive sulfide deposit is a small, metal-rich sulfide body hosted by Paleoproterozoic metavolcanics. The mineralized horizon subcrops beneath 100-120 feet of glacial cover, and consists of massive pyrite and other sulfides. Bedrock and ore geochemistry are well characterized by analyses of diamond drill core provided to the USGS by Sharpe Energy and Resources. In July 1999, five rotasonic drillholes were completed through the unconsolidated Quaternary sediment, averaging about 100 feet thick, on a transect across the Bend deposit. Nearly continuous core was recovered from the surficial material along with several feet of the underlying bedrock. Samples representing the entire section were analyzed by the USGS to give a two-dimensional representation of element dispersal from the unmineralized bedrock. In addition, one hundred regional till samples were subsampled from the archives of the Quaternary Sediment Laboratory in the University of Wisconsin-Madison Department of Geology and Geophysics. These regional samples were collected mainly from Taylor County, where the Bend deposit is located, as well as contiguous parts of Clark and Marathon Counties. This open file report presents all of the geochemical data collected for this study. Additional publications describing the data in more detail are being completed.

Wisconsin↗

USGS1953

Results of reconnaissance for radioactive minerals in parts of the Alma district, Park County, Colorado

Pitchblende was discovered in July 1951 in the Alma mining district, Park County, Colo., by the U. S. Geological Survey acting on behalf of the U. S. Atomic Energy Commission. The pitchblende is associated with Tertiary veins of three different geologic environments: (1) veins in pre-Cambrian rocks, (2) the London vein system in the footwall block of the London fault, and (3) veins in a mineralized area east of the Cooper Gulch fault. Pitchblende is probably not associated with silver-lead replacement deposits in dolomite. Secondary uranium minerals, as yet undetermined, are associated with pitchblende on two London vein system mine dumps and occur in oxidized vein material from dumps of mines in the other environments. Although none of the known occurrences is of commercial importance, the Alma district is considered a moderately favorable area in which to prospect for uranium ore because 24 of the 43 localities examined show anomalous radioactivity; samples from anomalously radioactive localities, which include mine dumps and some underground workings, have uranium contents ranging from 0.001 to 1.66 percent.

Circular↗

USGS1997

Coal-Quality Information - Key to the Efficient and Environmentally Sound Use of Coal

The rock that we refer to as coal is derived principally from decomposed organic matter (plants) consisting primarily of the element carbon. When coal is burned, it produces energy in the form of heat, which is used to power machines such as steam engines or to drive turbines that produce electricity. Almost 60 percent of the electricity produced in the United States is derived from coal combustion. Coal is an extraordinarily complex material. In addition to organic matter, coal contains water (up to 40 or more percent by weight for some lignitic coals), oils, gases (such as methane), waxes (used to make shoe polish), and perhaps most importantly, inorganic matter (fig. 1). The inorganic matter--minerals and trace elements--cause many of the health, environmental, and technological problems attributed to coal use (fig. 2). 'Coal quality' is the term used to refer to the properties and characteristics of coal that influence its behavior and use. Among the coal-quality characteristics that will be important for future coal use are the concentrations, distribution, and forms of the many elements contained in the coal that we intend to burn. Knowledge of these quality characteristics in U.S. coal deposits may allow us to use this essential energy resource more efficiently and effectively and with less undesirable environmental impact.

Fact Sheet↗

USGS2023

Assessment of lunar resource exploration in 2022

The idea of mining the Moon, once purely science-fiction, is now on the verge of becoming reality. Taking advantage of the resources on the Moon is part of the plans of many nations and some enterprising commercial entities; demonstrating in-situ (in place) resource utilization near the lunar south pole is an explicit goal of the United States’ Artemis program. Economic extraction and sustainable management of these resources require understanding the nature, quantity, and quality of each resource. This publication aims to provide a relatively simple, but technically rigorous, assessment of the status of lunar resource exploration in 2022. Building on the experience of the U.S. Geological Survey in conducting resource assessments for Earth, we propose a general methodology for quantitative lunar resources assessments. Lunar resources can be categorized as energy, mineral, and water and classified with respect to their certainty and their recoverability. The portion of the technically recoverable resource that can be converted to a commodity within budgetary and other mission constraints can be classified as a “reserve.” For energy resources, solar energy is known to be especially abundant along some high ridges near the lunar poles and the technology to exploit it is mature. Mineral resources, largely in the form of loose rock powder that covers the surface of the Moon, are also widely accessible in large quantities. Many different technologies to convert this material into useful commodities (such as landing pads and oxygen) are currently being developed and are likely to be available for industrial-scale application within 30 years. Water ice almost certainly exists in the polar regions of the Moon but there are fundamental unanswered questions about when and how the ice formed—leaving us without knowledge of the form, quantity, quality, and distribution of lunar ice. Until rover missions bring new ground truth data, lunar ice will remain a highly speculative resource that may be both limited and non-renewable.

Circular↗

USGS2015

Tellurium: providing a bright future for solar energy

Tellurium is one of the least common elements on Earth. Most rocks contain an average of about 3 parts per billion tellurium, making it rarer than the rare earth elements and eight times less abundant than gold. Grains of native tellurium appear in rocks as a brittle, silvery-white material, but tellurium more commonly occurs in telluride minerals that include varied quantities of gold, silver, or platinum. Tellurium is a metalloid, meaning it possesses the properties of both metals and nonmetals. Tellurium was discovered within gold ores in the late 1780s in Transylvania, Romania. Fifteen years later, the element was isolated as a distinct substance and named tellurium, after the Latin word “tellus,” which means “fruit of the Earth.” Recovered tellurium has historically been used in metallurgy as an additive to stainless steel and in alloys made with copper, lead, and iron. Because of its low abundance, little is known about environmental baseline concentrations for tellurium or its toxic effect on humans and ecosystems. Human exposure to tellurium can lead to a garlic odor on the breath, nausea, and eventual respiratory problems.

Fact Sheet↗

USGS1955

Engineering geology as applied to highway construction

A geologic study of the site for a relocated segment of State Highway 93 northwest of Denver Colo., was made by by the Engineering Geology Branch of the U.S. Geological Survey as a demonstration of the applicability of geologic mapping to problems of highway construction. The relocated segment provides access to the Rocky Flats plant of the Atomic Energy Commission. The geologic conditions along five miles of the relocation route were examined. In most places apparently well-indurated sandstones of the Upper Cretaceous Fox Hills sandstone and Laramie formation can be excavated without using explosives. The intersection of a six foot thick coal seam in the roadbed in one proposed cut was predicted and removal and replacement with more suitable subgrade material was recommended. Near Marshall the alignment crosses three northeast-trending normal faults which do not adversely affect the highway. Clay minerals with expanding properties are present in some of the claystones of the Laramie, and special measures must be taken to ensure that ground water will not seep into them and cause swelling beneath the roadbed. Late Tertiary or Early Quaternary gravel cap pediments along the mountain front. Ground water issuing from seeps and springs found at the contact between these gravels and the underlying bedrock should be intercepted and removed from beneath the roadbed.

Colorado↗

USGS1998

Remote sensing in the USGS Mineral Resource Surveys Program in the eastern United States

Mineral deposits commonly occur within special geologic units or structures, such as fault zones, which can be detected and mapped from aircraft and satellite images. Modern techniques analyze multispectral images that record the way solar energy is reflected or emitted by the materials exposed at the Earth's surface. In sparsely vegetated regions, including most of the Western United States, mineral composition is determined directly by analyzing the spectral properties of rock outcrops. In more densely vegetated terrain, such as the Eastern United States, rock and soil composition can be determined directly in manmade exposures, such as plowed fields and construction sites, or much more general determinations can be made indirectly by analyzing the distribution and apparent health of naturally occurring plants. The association of certain plants with particular rock or soil types has been known for decades. For example, coniferous trees grow preferentially on well-drained sandy soil, whereas deciduous trees dominate on shaly bedrock. These two forest types reflect solar radiation quite differently and, therefore, are distinguished readily in conventional aerial photographs. More subtle plant-bedrock associations require digital multispectral image analysis to infer compositional information from the spectral characteristics of the forest canopy.

Information Handout↗

USGS1973

Chemical interactions of aluminum with aqueous silica at 25 degrees Celsius

Solutions containing from 10 -5 to 10 -2 moles per liter of aluminum and dissolved silica in various ratios were aged at pH levels between 4 and 10 at 25?C. A colloidal amorphous product having the composition of halloysite was produced in most solutions. It had a consistent and reversible equilibrium solubility equivalent to a standard free energy of formation of -8974 ? 1.0 kcal per mole for the formula A12Si2O5(OH)4. Some aging times were longer than 4 years, but most solutions gave consistent solubilities after only a few months of aging. Where silica concentrations were below about 10 -4 molar, microcrystalline gibbsite was formed below pH 6.0 and crystalline bayerite above pH 7.0, but only after much longer aging than was required for crystallization in silica-free solutions. Electron micrographs and diffraction patterns of the synthesized material indicate some crystallinity in the aluminosilicate, but no X-ray diffraction patterns could be obtained even in the material aged 4 years. Solubility relationships for solutions containing fluoride as well as silica and aluminum are explainable by using cryolite stabilities determined in previous work. Aluminum contents of 51 samples of water analyzed for other purposes are in reasonable agreement with the assumption of equilibrium with amorphous clay mineral species similar to the material synthesized in this work. Solubility calculations are summarized graphically for solutions of ionic strength of 0.01 and 0.10.

Water Supply Paper↗

USGS1980

High-resolution seismic-reflection profiling data from the inner continental shelf of southeastern Massachusetts

Six hundred-seventy kilometers of closely spaced high-resolution seismic-reflection data have been collected from eastern Rhode Island Sound and Vineyard Sound, Mass, by the U.S. Geological Survey in cooperation with the Massachusetts Department of Public Works. These data were obtained during the June 1975 cruise of the R/V ASTERIAS as part of a continuing regional study of the Massachusetts offshore area to assess potential mineral resources, to evaluate environmental impact of mining of resources and of offshore disposal of solid waste and harbor dredge-spoil materials, and to map the offshore geology and shallow structure. The data were obtained by using a surface-towed EG&G Unit Pulse Boomer* (300 joules: 400 Hz-8kHz frequency) sound source. Reflected acoustic energy was detected by a 4.6-m, a-element hydrophone array, was amplified, was actively filtered (400 Hz-4kHz bandpass), and was graphically displayed on an EPC* dry paper recorder at a 0.25-second sweep rate. System resolution was generally 1 to 1.5 m. Navigational control was provided by Loran C (positional accuracy within 0.2 km) and was supplemented by radar and visual fixes. Positional information was logged at 15-minute intervals and at major course changes. The original records may be examined at the Data Library, U.S. Geological Survey, Woods Hole, MA 02543. Microfilm copies of the data are available for purchase from the National Geophysical and Solar-Terrestrial Data Center (NGSDC), Boulder, CO 80302.

Open-File Report↗

USGS2017

Critical mineral resources of the United States—An introduction

Many changes have taken place in the mineral resource sector since the publication by the U.S. Geological Survey of Professional Paper 820, “United States Mineral Resources,” which is a review of the long-term United States resource position for 65 mineral commodities or commodity groups. For example, since 1973, the United States has continued to become increasingly dependent on imports to meet its demands for an increasing number of mineral commodities. The global demand for mineral commodities is at an alltime high and is expected to continue to increase, and the development of new technologies and products has led to the use of a greater number of mineral commodities in increasing quantities to the point that, today, essentially all naturally occurring elements have several significant industrial uses. Although most mineral commodities are present in sufficient amounts in the earth to provide adequate supplies for many years to come, their availability can be affected by such factors as social constraints, politics, laws, environmental regulations, land-use restrictions, economics, and infrastructure. This volume presents updated reviews of 23 mineral commodities and commodity groups viewed as critical to a broad range of existing and emerging technologies, renewable energy, and national security. The commodities or commodity groups included are antimony, barite, beryllium, cobalt, fluorine, gallium, germanium, graphite, hafnium, indium, lithium, manganese, niobium, platinum-group elements, rare-earth elements, rhenium, selenium, tantalum, tellurium, tin, titanium, vanadium, and zirconium. All these commodities have been listed as critical and (or) strategic in one or more of the recent studies based on assessed likelihood of supply interruption and the possible cost of such a disruption to the assessor. For some of the minerals, current production is limited to only one or a few countries. For many, the United States currently has no mine production or any significant identified resources and is largely dependent on imports to meet its needs. As a result, the emphasis in this volume is on the global distribution and availability of each mineral commodity. The environmental issues related to production of each mineral commodity, including current mitigation and remediation approaches to deal with these challenges, are also addressed. This introductory chapter provides an overview of the mineral resource classifications, terms, and definitions used in this volume. A review of the history of the use and meaning of the term “critical” minerals (or materials) is included as an appendix to the chapter.

Professional Paper↗

USGS2025

Characterizing Meteor Crater impact melts through geochemistry and textural analysis

The U.S. Geological Survey Astrogeology Science Center houses the Meteor Crater sample collection, an assemblage of over 2,500 meters of cuttings from 161 drill holes into Meteor Crater’s rim, flanks, and ejecta blanket. We have utilized this unique collection to study the composition and spatial distribution of impact-generated materials from within the ejecta blanket. Meteor Crater has historically been known to have generated only a relatively small amount of impact melt compared to other terrestrial craters of similar size. A detailed compositional and textural dataset of impact-derived melts from this impact can therefore be a useful asset in improving our understanding of crater formation, and in particular impact melt formation. We have characterized 42 impact-melt particles from Meteor Crater using a scanning electron microscope and an electron microprobe for textural and compositional analysis. We analyzed samples from six drill holes in the ejecta blanket, situated to the northwest, southeast, south, and southwest of the crater (ejecta northeast of the crater is devoid of impact melts). Impact melts were collected from drill cuttings at various depths within the ejecta blanket, ranging from a few centimeters below the surface down to ~6.5 meters. Backscattered electron (BSE) images were acquired for each analyzed impact-melt particle. To characterize the various textures and phases present in each impact melt, we also took many detailed BSE images. Our geochemical analyses include full spectral profiles using energy dispersive X-ray spectrometry and well-calibrated wavelength dispersive spectrometry for a number of phases, including minerals (olivine, pyroxene, and so on), pristine glass, and metallic inclusions. The full dataset is available in ScienceBase as a data release (Gullikson and others, 2024), accessible at https://doi.org/10.5066/P9OGAJ8P . Our goal for this Open-File Report is to provide a summary of this immense dataset, details on data collection, descriptions of the different phases observed within impact-melt particles (both geochemically and texturally), and observable trends.

Arizona↗

USGS2004

Mineral, Energy, and Fertilizer Resources of the North Coast of Peru: Perspective from the Santa Rita B Archaeological Site

The Santa Rita B archaeological site is in the Chao Valley, approximately 65 km southeast of Trujillo, northern Peru. Location of Santa Rita B at the emergence of several drainages from the Andean cordillera is an important factor in the almost continuous occupation of the site over the past 3,000 years. Mineral resources are abundant throughout the Andes; however, the north coast of Peru was an important center for pre-Columbian mining, metallurgy, and craftsmanship. Success of the Chavin, Moche, Chimu, and other north coast cultures is directly related to the availability and exploitation of mineral and energy resources that include: gold (?silver), as electrum, mainly from placers, and copper from local oxide and carbonate occurrences and from sulfides related to copper porphyry occurrences in the cordillera. An alloy of these three metals is referred to as tumbaga, which is the primary material for Andean metalcraft. Anthracite was used for mirrors by north coast cultures and is available near Rio Chicama, Rio Santa, and east of Santa Rita B. These outcrops are a part of the Alto Chicama, Peru's largest coalfield, which extends from Rio Chicama, in the north, for 200 km southward to Rio Santa. Charcoal from the algorrobo tree and llama dung are considered to be the common pre-Columbian energy sources for cooking and metalwork; however, availability and the higher heat content of anthracite indicate that it was used in metallurgical applications. Bitumen is available from petroleum seeps near Talara, north of the study area, and may have been used as glue or as cement. Hematite, goethite, limonite, and manganese oxides from clay-altered volcanic rock may have provided color and material for ceramics. Guano from the Islas Gua?apes, Chinchas, and Ballestas was used as fertilizer for cotton and other crops.

Open-File Report↗

USGS1989

Mineralogy and grain size of surficial sediment from the Big Lost River drainage and vicinity, with chemical and physical characteristics of geologic materials from selected sites at the Idaho National Engineering Laboratory, Idaho

The U.S. Geological Survey 's Idaho National Engineering Laboratory project office, in cooperation with the U.S. Department of Energy, collected 35 samples of surficial sediments from the Big Lost River drainage and vicinity from July 1987 through August 1988 for analysis of grain-size distribution, bulk mineralogy, and clay mineralogy. Samples were collected from 11 sites in the channel and 5 sites in overbank deposits of the Big Lost River, 6 sites in the spreading areas that receive excess flow from the Big Lost River during peak flow conditions, 7 sites in the natural sinks and playas of the Big Lost River, 1 site in the Little Lost River Sink, and 5 sites from other small, isolated closed basins. Eleven samples from the Big Lost River channel deposits had a mean of 1.9 and median of 0.8 weight percent in the less than 0.062 mm fraction. The other 24 samples had a mean of 63.3 and median of 63.7 weight percent for the same size fraction. Mineralogy data are consistent with grain-size data. The Big Lost River channel deposits had mean and median percent mineral abundances of total clays and detrital mica of 10 and 10%, respectively, whereas the remaining 24 samples had mean and median values of 24% and 22.5% , respectively. (USGS)

Open-File Report↗

USGS2017

Niobium and tantalum

Niobium and tantalum are transition metals that are almost always found together in nature because they have very similar physical and chemical properties. Their properties of hardness, conductivity, and resistance to corrosion largely determine their primary uses today. The leading use of niobium (about 75 percent) is in the production of high-strength steel alloys used in pipelines, transportation infrastructure, and structural applications. Electronic capacitors are the leading use of tantalum for high-end applications, including cell phones, computer hard drives, and such implantable medical devices as pacemakers. Niobium and tantalum are considered critical and strategic metals based on the potential risks to their supply (because current production is restricted to only a few countries) and the significant effects that a restriction in supply would have on the defense, energy, high-tech industrial, and medical sectors. The average abundance of niobium and tantalum in bulk continental crust is relatively low—8.0 parts per million (ppm) niobium and 0.7 ppm tantalum. Their chemical characteristics, such as small ionic size and high electronic field strength, significantly reduce the potential for these elements to substitute for more common elements in rock-forming minerals and make niobium and tantalum essentially immobile in most aqueous solutions. Niobium and tantalum do not occur naturally as pure metals but are concentrated in a variety of relatively rare oxide and hydroxide minerals, as well as in a few rare silicate minerals. Niobium is primarily derived from the complex oxide minerals of the pyrochlore group ((Na,Ca,Ce) 2 (Nb,Ti,Ta) 2 (O,OH,F) 7 ), which are found in some alkaline granite-syenite complexes (that is, igneous rocks containing sodium- or potassium-rich minerals and little or no quartz) and carbonatites (that is, igneous rocks that are more than 50 percent composed of primary carbonate minerals, by volume). Tantalum is derived mostly from the mineral tantalite ((Fe,Mn)(Ta,Nb) 2 O 6 ), which is found as an accessory mineral in rare-metal granites and pegmatites that are also enriched in lithium and cesium (termed lithium-cesium-tantalum (LCT)-type pegmatites). Brazil and Canada are the leading nations that produce niobium mineral concentrates, but Brazil is by far the leading producer, accounting for about 90 percent of production, which comes mostly from weathered material derived from carbonatites. Brazil and Canada also have the largest identified niobium resources; additional resources, although they are less well reported, occur in Angola, Australia, China, Greenland, Malawi, Russia, and South Africa. Australia and Brazil have been the leading producers of tantalum mineral concentrates, although recently Ethiopia and Mozambique have also been significant suppliers of tantalum. Artisanal mining of columbite-tantalite (also called coltan) is practiced in many countries, particularly Burundi, the Democratic Republic of the Congo (Congo [Kinshasa]), Nigeria, Rwanda, and Uganda. Brazil has about 40 percent of the identified tantalum resources; other countries and regions with identified tantalum resources include, in decreasing order of resources, Australia, Asia, Russia and the Middle East, Africa, North America, and Europe. Identified niobium and tantalum resources in the United States are small, low grade, and difficult to recover and process, and are thus not commercially recoverable at current prices. Consequently, the United States meets its current and expected future needs for niobium and tantalum through imports of primary mineral concentrates and alloys and through recovery from foreign and domestic alloy scrap that contain the metals. Environmentally, the main issues related to niobium and tantalum mining are land disruptions, the volume of waste materials and their disposal, and the radioactivity of some tailings and waste materials that contain thorium and uranium. Because of the relative biological inertness of niobium and tantalum, human and ecological health concerns are generally minimal under most natural conditions. Demand for both niobium and tantalum is expected to increase as the world economy continues to recover from the downturn that began in 2008. Increased demand for niobium is linked to increased consumption of microalloyed steel, which is used in the manufacture of cars, buildings, ships, and refinery equipment. Demand for these steels will likely increase with continued economic development in such countries as Brazil, China, and India. In addition, increased global demand for cars, cell phones, computers, superconducting magnets, and other high-tech devices will likely spur increased demand for both niobium and tantalum. The estimated global reserves and resources of niobium and tantalum are large and appear more than sufficient to meet global demand for the foreseeable future, possibly the next 500 years. The sale of “conflict coltan” attributed to rebel forces waging a civil war in Congo (Kinshasa) has been of recent concern and has highlighted the need for a transparent and traceable global supply chain that can exclude illegal columbite-tantalite from the conventional market while discerning legitimate artisanal mine production in central Africa.

Professional Paper↗