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At least 289 records · Page 16Linked to original sources
USGS2013

Local-area-enhanced, 2.5-meter resolution natural-color and color-infrared satellite-image mosaics of the Bakhud mineral district in Afghanistan: Chapter U in Local-area-enhanced, high-resolution natural-color and color-infrared satellite-image mosaics of mineral districts in Afghanistan

The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Defense Task Force for Business and Stability Operations, prepared databases for mineral-resource target areas in Afghanistan. The purpose of the databases is to (1) provide useful data to ground-survey crews for use in performing detailed assessments of the areas and (2) provide useful information to private investors who are considering investment in a particular area for development of its natural resources. The set of satellite-image mosaics provided in this Data Series (DS) is one such database. Although airborne digital color-infrared imagery was acquired for parts of Afghanistan in 2006, the image data have radiometric variations that preclude their use in creating a consistent image mosaic for geologic analysis. Consequently, image mosaics were created using ALOS (Advanced Land Observation Satellite; renamed Daichi) satellite images, whose radiometry has been well determined (Saunier, 2007a,b). This part of the DS consists of the locally enhanced ALOS image mosaics for the Bakhud mineral district, which has industrial fluorite deposits. ALOS was launched on January 24, 2006, and provides multispectral images from the AVNIR (Advanced Visible and Near-Infrared Radiometer) sensor in blue (420–500 nanometer, nm), green (520–600 nm), red (610–690 nm), and near-infrared (760–890 nm) wavelength bands with an 8-bit dynamic range and a 10-meter (m) ground resolution. The satellite also provides a panchromatic band image from the PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) sensor (520–770 nm) with the same dynamic range but a 2.5-m ground resolution. The image products in this DS incorporate copyrighted data provided by the Japan Aerospace Exploration Agency (©JAXA,2006,2007, 2008), but the image processing has altered the original pixel structure and all image values of the JAXA ALOS data, such that original image values cannot be recreated from this DS. As such, the DS products match JAXA criteria for value added products, which are not copyrighted, according to the ALOS end-user license agreement. The selection criteria for the satellite imagery used in our mosaics were images having (1) the highest solar-elevation angles (near summer solstice) and (2) the least cloud, cloud-shadow, and snow cover. The multispectral and panchromatic data were orthorectified with ALOS satellite ephemeris data, a process which is not as accurate as orthorectification using digital elevation models (DEMs); however, the ALOS processing center did not have a precise DEM. As a result, the multispectral and panchromatic image pairs were generally not well registered to the surface and not coregistered well enough to perform resolution enhancement on the multispectral data. Therefore, it was necessary to (1) register the 10-m AVNIR multispectral imagery to a well-controlled Landsat image base, (2) mosaic the individual multispectral images into a single image of the entire area of interest, (3) register each panchromatic image to the registered multispectral image base, and (4) mosaic the individual panchromatic images into a single image of the entire area of interest. The two image-registration steps were facilitated using an automated control-point algorithm developed by the USGS that allows image coregistration to within one picture element. Before rectification, the multispectral and panchromatic images were converted to radiance values and then to relative-reflectance values using the methods described in Davis (2006). Mosaicking the multispectral or panchromatic images started with the image with the highest sun-elevation angle and the least atmospheric scattering, which was treated as the standard image. The band-reflectance values of all other multispectral or panchromatic images within the area were sequentially adjusted to that of the standard image by determining band-reflectance correspondence between overlapping images using linear least-squares analysis. The resolution of the multispectral image mosaic was then increased to that of the panchromatic image mosaic using the SPARKLE logic, which is described in Davis (2006). Each of the four-band images within the resolution-enhanced image mosaic was individually subjected to a local-area histogram stretch algorithm (described in Davis, 2007), which stretches each band’s picture element based on the digital values of all picture elements within a 315-m radius. The final databases, which are provided in this DS, are three-band, color-composite images of the local-area-enhanced, natural-color data (the blue, green, and red wavelength bands) and color-infrared data (the green, red, and near-infrared wavelength bands). All image data were initially projected and maintained in Universal Transverse Mercator (UTM) map projection using the target area’s local zone (41 for Bakhud) and the WGS84 datum. The final image mosaics were subdivided into nine overlapping tiles or quadrants because of the large size of the target area. The nine image tiles (or quadrants) for the Bakhud area are provided as embedded geotiff images, which can be read and used by most geographic information system (GIS) and image-processing software. The tiff world files (tfw) are provided, even though they are generally not needed for most software to read an embedded geotiff image.

Data Series↗
USGS1990

Hydrogeology of the Pictured Cliffs Sandstone in the San Juan structural basin, New Mexico, Colorado, Arizona, and Utah

This report is one in a series resulting from the U.S. Geological Survey's Regional Aquifer System Analysis (RASA) study of the San Juan structural basin that began in October 1984. The purposes of the study (Welder, 1986) are to: (1) Define and evaluate the aquifer system; (2) assess the effects of past, present, and potential ground-water use on aquifers and streams, and (3) determine the availability and quality of ground water. Previous reports in this series describe the hydrogeology of the Dakota Sandstone (Craigg and others, 1989), Gallup Sandstone (Kernodle and others, 1989), Morrison Formation (Dam and others, 1990), Point Lookout Sandstone (Craigg and others, 1990), Kirtland Shale and Fruitland Formation (Kernodle and others, 1990), Menefee Formation (Levings and others, 1990), Cliff House Sandstone (Thorn and others, 1990), and Ojo Alamo Sandstone (Thorn and others, 1990) in the San Juan structural basin. This report summarizes information on the geology and the occurrence and quality of water in the Pictured Cliffs Sandstone, one of the primary water-bearing units in the regional aquifer system. Data used in this report were collected during the RASA study or derived from existing records in the U.S. Geological Survey's computerized National Water Information System (NWIS) data base, the Petroleum Information Corporation's data base, and the Dwight's ENERGYDATA Inc. BRIN database. Although all data available for the Pictured Cliffs Sandstone were considered in formulating the discussions in the text, not all those data could be plotted on the illustrations. The San Juan structural basin in New Mexico, Colorado, Arizona, and Utah has an area of about 21,600 square miles (fig. 1). The structural basin is about 140 miles wide and about 200 miles long. The study area is that part of the structural basin that contains rocks of Triassic and younger age; therefore, the study area is less extensive than the structural basin. Triassic through Tertiary sedimentary rocks are emphasized in this study because these units are the major aquifers in the basin. The study area is about 140 miles wide (about the same as the structural basin), 180 miles long, and has an area of about 19,400 square miles. Altitudes in the study area range from about 4,500 feet in southeastern Utah, to about 11,000 feet in the southeastern part of the basin. The area-weighted mean altitude is about 6,700 feet. Annual precipitation in the high mountainous areas along the north and east margins of the basin is as much as 45 inches, whereas annual precipitation in the lower altitude, central basin is generally less than 8 inches. Mean annual precipitation is about 12 inches. Data obtained from documents published by the U.S. Bureau of the Census (1980 and 1985) were used to calculate the population of the study area. The population in 1970 was calculated to be about 134,000. The population increased to about 194,000 in 1980,212,000 in 1982,221,000 in 1984, and then declined to about 210,000 in 1985. The economy of the basin is supported by exploration and development of natural gas, petroleum, coal, and uranium resources; urban enterprise; farming and ranching tourism, and recreation. The rise and fall in population were related to changes in the economic strength of the minerals, oil, and gas industries, and support services. Uranium-mining and -milling activities underwent rapid growth until the late 1970's when most uranium-mining activity came to an abrupt end. Likewise, the oil and gas industry prospered until about 1983 and then declined rapidly.

Hydrologic Atlas↗
USGS2010

Seamount mineral deposits: A source of rare metals for high technology industries

The near exponential growth in Earth’s population and the global economy puts increasing constraints on our planet’s finite supply of natural metal resources, and, consequently, there is an increasing need for new sources to supply high-tech industries. To date, effectively all of our raw-metal resources are produced at land-based sites. Except for nearshore placer deposits, the marine environment has been largely excluded from metal mining due to technological difficulties, even though it covers more than 70% of the planet. The case can be made that deep-water seabed mining is inevitable in the future, owing to the critical and strategic metal needs for human society. In this paper, we evaluate the case that seamounts offer significant potential for mining.

Oceanography↗
USGS1985

MARINE MINERAL RESOURCES - AN UPDATE AND INTRODUCTION.

This article briefly traces the status of marine minerals development, and it describes papers presented in this special issue on the subject. Subjects covered include types of deposits, marine mining in Canada, Manganese nodules, metalliferous sulfides as seabed minerals, metallurgical processes for reducing sulfide minerals, U. S. phosphate industry, construction materials and placers, and industry problems.

Marine Technology Society Journal↗
USGS2012

Mineral resource of the month: mercury

The article offers information on mercury, a mineral commodity used in industrial and small-scale gold mining applications. Mercury has been reported to be used for amalgamation with gold since the Roman times. Mercury from cinnabar from Almadén, Spain has been used by Romans and has been continued to be used through the Middle Ages and the Colonial era.

Earth↗
USGS1996

A watershed-scale approach to tracing metal contamination in the environment

Introduction Public policy during the 1800's encouraged mining in the western United States. Mining on Federal lands played an important role in the growing economy creating national wealth from our abundant and diverse mineral resource base. The common industrial practice from the early days of mining through about 1970 in the U.S. was for mine operators to dispose of the mine wastes and mill tailings in the nearest stream reach or lake. As a result of this contamination, many stream reaches below old mines, mills, and mining districts and some major rivers and lakes no longer support aquatic life. Riparian habitats within these affected watersheds have also been impacted. Often, the water from these affected stream reaches is generally not suitable for drinking, creating a public health hazard. The recent Department of Interior Abandoned Mine Lands ( AML ) Initiative is an effort on the part of the Federal Government to address the adverse environmental impact of these past mining practices on Federal lands. The AML Initiative has adopted a watershed approach to determine those sites that contribute the majority of the contaminants in the watershed. By remediating the largest sources of contamination within the watershed, the impact of metal contamination in the environment within the watershed as a whole is reduced rather than focusing largely on those sites for which principal responsible parties can be found. The scope of the problem of metal contamination in the environment from past mining practices in the coterminous U.S. is addressed in a recent report by Ferderer (1996). Using the USGS 1:2,000,000-scale hydrologic drainage basin boundaries and the USGS Minerals Availability System ( MAS ) data base, he plotted the distribution of 48,000 past-producing metal mines on maps showing the boundaries of lands administered by the various Federal Land Management Agencies ( FLMA ). Census analysis of these data provided an initial screening tool for prioritization of watersheds in the western U.S. A different approach to the scope of the abandoned mine problem (Church et al., 1996a) is shown by the water quality data collected by the States under the Clean Water Act, section 305(b). These data document the stream reaches affected by metals from naturally occurring sources as well as from mining, or mineral resource extraction. Permitted discharges from active industrial and mine sites are not covered in the 305(b) data base. Local citizens and state and federal agencies are all part of the collaborative decision process used to select the drainage basins chosen for the AML Initiative pilot studies. Data gathered by these three entities were brought to bear on the watershed selection process. The USGS prepared data available from Federal data bases in the form of interpretative GIS products. Maps of the states of Colorado (Plumlee et al., 1995) and a similar study of the state of Montana ( USGS , unpublished data) were used to select the Animas watershed in southwestern Colorado and the Boulder watershed southwest of Helena Montana as the pilot study areas for the AML Initiative. Thus, the watersheds selected for study were public decisions made on the basis of available scientific data. The role of the U.S. Geological Survey in the Abandoned Mine Land Initiative is outlined in Buxton et al. (1997). The watershed approach to metals contamination in the environment has been studied in several drainage basins (Church et al., 1993, 1994, 1995, 1996b; Kimball et al., 1995). The underlying principles used to successfully discriminate between sources and to quantify the impact of these sources on the environment are the subject of this report.

Conference Paper↗
USGS2025

Critical Minerals in Ores (CMiO) database

Critical minerals are commodities essential to modern industrial and strategic technologies and are highly vulnerable to supply chain disruption. The Critical Minerals Mapping Initiative (CMMI) is a collaboration among the U.S. Geological Survey (USGS), the Geological Survey of Canada, and Geoscience Australia that aims to deepen global understanding of where critical minerals are located. A key output of this initiative is the Critical Minerals in Ores (CMiO) database that is advancing our collective understanding of critical minerals distributions. For instance, publicly available data on the concentrations of many critical minerals are sparse because these commodities can only be produced in small, yet essential, quantities compared to the primary commodities like copper and zinc. The CMiO database helps bridge this gap by offering high-quality, multielement geochemical data from a wide variety of critical mineral-bearing deposits around the world. Importantly, it uses a novel consensus deposit environment, group, and type classification scheme developed by the agencies that allows comparisons among ore deposits from different regions. The CMiO database contains geochemical data for more than 20,000 samples from more than 100 deposit types comprising 10 deposit environments.

Fact Sheet↗
USGS1998

Database of significant deposits of gold, silver, copper, lead, and zinc in the United States

It has long been recognized that the largest mineral deposits contain most of the known mineral endowment (Singer and DeYoung, 1980). Sometimes called giant or world-class deposits, these largest deposits account for a very large share of historic and current mineral production and resources in industrial society (Singer, 1995). For example, Singer (1995) shows that the largest 10 percent of the world’s gold deposits contain 86 percent of the gold discovered to date. Many mineral resource issues and investigations are more easily addressed if limited to the relatively small number of deposits that contain most of the known mineral resources. An estimate of known resources using just these deposits would normally be sufficient, because considering smaller deposits would not add significantly to the total estimate. Land-use planning should treat mainly with these deposits due to their relative scarcity, the large share of known resources they contain, and the fact that economies of scale allow minerals to be produced much more cheaply from larger deposits. Investigation of environmental and other hazards that result from mining operations can be limited to these largest deposits because they account for most of past and current production. The National Mineral Resource Assessment project of the U.S. Geological Survey (USGS) has compiled a database on the largest known deposits of gold, silver, copper, lead, and zinc in the United States to complement the 1996 national assessment of undiscovered deposits of these same metals (Ludington and Cox, 1996). The deposits in this database account for approximately 99 percent of domestic production of these metals and probably a similar share of identified resources. These data may be compared with results of the assessment of undiscovered resources to characterize the nation’s total mineral endowment for these metals. This database is a starting point for any national or regional mineral-resource or mineral-environmental investigation.

Open-File Report↗
USGS2007

Lead (Pb) in old Antarctic ice: Some from dust, some from other sources

Recently published data on amounts and isotopic compositions of lead (Pb) and on amounts of mineral dust in pre-industrial Antarctic ice can be further interpreted by means of simple calculations. These show that two distinct types of Pb were provided by the atmosphere to the continent in varying proportions during Pleistocene and Holocene time. One type of Pb is that contained in the mineral lattices of dust. It has non-radiogenic isotopic proportions. The other type of Pb is not associated with dust minerals, is more radiogenic, and is consistent with an origin in emissions from ocean island volcanoes worldwide, or from some Antarctic volcanoes.

Geophysical Research Letters↗
USGS2022

Tungsten skarn potential of the Yukon-Tanana Upland, eastern Alaska, USA—A mineral resource assessment

Tungsten (W) is used in a variety of industrial and technological applications and has been identified as a critical mineral for the United States, India, the European Union, and other countries. These countries rely on W imports mostly from China, which leaves them vulnerable to supply disruption. Consequently, the U.S. government has a current initiative to understand domestic resource potential. The eastern Alaska portion of the Yukon-Tanana Upland (YTU), is prospective for W skarn deposits, the major source of global W supply. The regional geology consists of juxtaposed Paleozoic lithotectonic packages that were reaccreted to North America in the Mesozoic . Multiple subsequent episodes of arc-related magmatism intruded the lithotectonic packages, accompanied by W skarn formation mostly associated with 100–90 Ma intrusions; major W skarn deposits in Canada are part of the same metallogenic event (e.g., Mactung, Cantung). In this paper, we present an assessment for undiscovered W skarn resources for parts of the lesser-explored western (Alaskan) portion of the YTU. We used GIS proximity analysis to map the intersection of pluton and carbonate-bearing rocks to define three permissive tracts for W skarn deposits. The permissive tracts were qualitatively assessed by mineral potential mapping using region-wide sediment geochemistry and mineral concentrate datasets. This analysis showed that much of the western YTU has high potential for undiscovered W skarn deposits, whereas the eastern and southern YTU had only isolated areas of medium to high potential. Historical production and the quality of the geochemistry data of the western YTU tract (ca. 9200 km 2 ) permitted a quantitative assessment of undiscovered W resources. Probabilistic estimates by a panel of 20 experts predicted a 70% chance of one to three undiscovered W skarn deposits in the western YTU tract. The rationale for favorability employed by the expert panel included favorable lithology, previous production, clustering of previously mined deposits, W placers in the area, lack of recent exploration, pan concentrates containing W minerals, and W geochemical anomalies. Estimates were combined with a global grade and tonnage model for W skarns in a Monte Carlo simulation and provided a median estimate of undiscovered resources of 94 kt WO 3 . If the undiscovered W skarn deposits are located close to infrastructure (e.g., near Fairbanks, or close to roads and/or power grid), application of an economic filter indicates that the median total economically recoverable WO 3 is 63 kt with a net present value (NPV) of $330 million USD (2008 dollars). Whereas if deposits are far from infrastructure, median recoverable WO 3 is only 30 kt and the NPV is $44 million. Our models for contained WO 3 resources and NPV estimates for the western YTU tract are considerably lower than the known resources in skarns in adjacent areas in Canada. Estimates for the western YTU are also lower than preliminary estimates for undiscovered W skarn deposits in areas of the western conterminous United States. We speculate that lower permeability and continuity of favorable carbonate rock horizons in the relatively higher-grade metamorphic country rocks in the Alaska portion of the YTU may explain some of the differences in prospectivity. More detailed geologic mapping, modern geochemistry, and geophysical surveys are needed to refine the resource potential of the whole YTU. Regardless, quantitative mineral resource assessment provides a useful tool for making first-order regional estimates of undiscovered resources, identifying target areas for new data acquisition, and guiding research on the fundamental controls of district-scale metallogenic endowments.

Alaska↗
USGS2007

Nanotechnology - An emerging technology

The science of nanotechnology is still in its infancy. However, progress is being made in research and development of potential beneficial properties of nanomaterials that could play an integral part in the development of new and changing uses for mineral commodities. Nanotechnology is a kind of toolbox that allows industry to make nanomaterials and nanostructures with special properties. New nanotechnology applications of mineral commodities in their nanoscale form are being discovered, researched and developed. At the same time, there is continued research into environmental, human health and safety concerns that inherently arise from the development of a new technology. Except for a few nanomaterials (CNTs, copper, silver and zinc oxide), widespread applications are hampered by processing and suitable commercial-scale production techniques, high manufacturing costs, product price, and environmental, and human health and safety concerns. Whether nanotechnology causes a tidal wave of change or is a long-term evolutionary process of technology, new applications of familiar mineral commodities will be created. As research and development continues, the ability to manipulate matter at the nanoscale into increasingly sophisticated nanomaterials will improve and open up new possibilities for industry that will change the flow and use of mineral commodities and the materials and products that are used.

Mining Engineering↗
USGS2014

Conflict minerals from the Democratic Republic of the Congo: global tungsten processing plants, a critical part of the tungsten supply chain

The U.S. Geological Survey (USGS) analyzes supply chains to identify and define major components of mineral and material flows from ore extraction, through intermediate forms, to a final product. Two major reasons necessitate these analyses: (1) to identify risks associated with the supply of critical and strategic minerals to the United States and (2) to provide greater supply chain transparency so that policymakers have the information necessary to ensure domestic legislation compliance. This fact sheet focuses on the latter. The USGS National Minerals Information Center has been asked by governmental and non-governmental organizations to provide information on tin, tantalum, tungsten, and gold (collectively known as “3TG minerals”) processing facilities worldwide in response to U.S. legislation aimed at removing the link between the trade in these minerals and civil unrest in the Democratic Republic of the Congo. Post beneficiation processing plants (smelters and refineries) of 3TG mineral ores and concentrates were identified by company and industry association representatives as being the link in the 3TG mineral supply chain through which these minerals can be traced to their source of origin (mine); determining the point of origin is critical to establishing a transparent conflict mineral supply chain. This fact sheet, the first in a series of 3TG mineral fact sheets, focuses on the tungsten supply chain by listing plants that consume tungsten concentrates to produce ammonium paratungstate and ferrotungsten worldwide.

Fact Sheet↗
USGS2014

Conflict minerals from the Democratic Republic of the Congo: global tantalum processing plants, a critical part of the tantalum supply chain

The U.S. Geological Survey (USGS) analyzes mineral and metal supply chains to identify and describe major components of mineral and metal material flows from ore extraction, through intermediate forms, to a final product. Supply chain analyses may be used (1) to identify risks to the United States associated with the supply of critical and strategic minerals and metals and (2) to provide greater supply chain transparency so that policymakers have the fact-based information needed to formulate public policy. This fact sheet focuses on the post-mining/pre-consumer-product part of the tantalum supply chain. The USGS National Minerals Information Center (NMIC) has been asked by governmental and non-governmental organizations to provide information about tantalum, tin, tungsten, and gold (collectively known as “3TG minerals”) processing facilities worldwide in response to U.S. legislation aimed at identifying and removing the supply chain links between the trade in these minerals and civil unrest in the Democratic Republic of the Congo and adjacent countries. Post-beneficiation processing plants (generally called smelters and refineries) for 3TG mineral ores and concentrates were identified by company and industry association representatives as being the link in the 3TG mineral supply chain through which these minerals can be traced to their source of origin (mine). The determination of the source of origin is critical to the development of a complete and transparent conflict-free mineral supply chain. Tungsten processing plants were the subject of the first fact sheet in this series published by USGS NMIC in August 2014. Background information about historical conditions and multinational stakeholders’ voluntary due diligence guidance for minerals from conflict-affected and high-risk areas is presented in the tungsten fact sheet. This fact sheet, the second in a series about 3TG minerals, focuses on the tantalum supply chain by listing selected processors that produced tantalum materials commercially worldwide during 2013–14. It does not provide any information regarding the sources of material processed in these facilities.

Fact Sheet↗
USGS2015

Conflict minerals from the Democratic Republic of the Congo—Tin processing plants, a critical part of the tin supply chain

Summary The U.S. Geological Survey (USGS) analyzes mineral and metal supply chains to identify and describe major components of material flows from ore extraction, through intermediate forms, to a final product. Supply chain analyses may be used (1) to identify risks to the United States associated with the supply of critical and strategic minerals and metals and (2) to provide greater supply chain transparency so that policymakers have the fact-based information needed to formulate public policy. This fact sheet focuses on the post-mining/pre-consumer-product part of the tin supply chain. The USGS National Minerals Information Center (NMIC) has been asked by governmental and non-governmental organizations to provide information about tantalum, tin, tungsten, and gold (collectively known as “3TG minerals”) processing facilities worldwide in response to U.S. legislation aimed at identifying and removing the supply chain links between the trade in these minerals and civil unrest in the Democratic Republic of the Congo (DRC) and adjacent countries. Post-beneficiation processing plants (generally called smelters and refineries) for 3TG mineral ores and concentrates were identified by company and industry association representatives as being a link in the 3TG mineral supply chain through which these minerals can be traced to their source of origin (mine). The determination of the source of origin is critical to the development of a complete and transparent conflict-free mineral supply chain. Tungsten processing plants were the subject of the first fact sheet in this series published by the USGS NMIC in August 2014. Background information about historical conditions and multinational stakeholders’ voluntary due diligence guidance for minerals from conflict-affected and high-risk areas was presented in the tungsten fact sheet. Tantalum processing plants were the subject of the second fact sheet in this series published by the USGS NMIC in December 2014. This fact sheet, the third in the series about 3TG minerals, focuses on the tin supply chain by listing selected processors that produced tin materials commercially worldwide during 2013–14. It does not provide any information regarding the sources of the material processed in these facilities.

Fact Sheet↗
USGS2015

Conflict minerals from the Democratic Republic of the Congo—Gold supply chain

The U.S. Geological Survey (USGS) analyzes mineral and metal supply chains to identify and describe major components of material flows from ore extraction, through intermediate forms, to a final product. Supply chain analyses may be used to identify risks to the United States associated with the supply of critical and strategic minerals and metals and to provide greater supply chain transparency so that policymakers have the fact-based information needed to formulate public policy. This fact sheet focuses on the gold supply chain. The USGS National Minerals Information Center (NMIC) has been asked by governmental and non-governmental organizations to provide information about tantalum, tin, tungsten, and gold (collectively known as “3TG minerals” ) processing facilities worldwide in response to U.S. legislation aimed at identifying and removing the supply chain links associated with the trade of these metals and minerals among armed groups in the Democratic Republic of the Congo (DRC) and adjacent countries. Post-beneficiation processing plants (generally called smelters and refineries) for tantalum, tin, and tungsten (3T) mineral ores and concentrates were identified by company and industry association representatives as being the link in the 3T mineral supply chain through which these minerals can be traced to their source of origin (mine). Tungsten processing plants were the subject of the first fact sheet in a series of USGS reports about 3TG minerals, which was published by the NMIC in August 2014 (Bermúdez-Lugo, 2014). Background information about historical conditions and the voluntary due diligence of multinational stakeholders for minerals from conflict-affected and high-risk areas is presented in the tungsten fact sheet. The current fact sheet, the fourth and last in the series about 3TG minerals, focuses on the gold supply chain. Processing of the 3T mineral concentrates requires substantial infrastructure and capital and generally is done at relatively few specialized facilities that are not located at the mine site; primary and secondary processors typically are at separate locations. Gold, however, can easily be processed into semi-refined products at or near the mine site and has a high unit value in any form, which allows it to be readily exported through undocumented channels, making it more difficult to track to the mine or region of origin. To put this in perspective, 30 kilograms (66 pounds) of 83 percent pure gold (20 carat) would form a cube measuring 12 centimeters per side (about the size of a small tissue box) and, at a price of $1,200 per ounce, would be worth nearly $1 million. By contrast, the equivalent value of tungsten concentrates would weigh about 45 metric tons (t) (100,000 pounds). Once conflict sourced gold has been combined with gold from other mines and scrap at a refiner, there is no feasible way to distinguish the source of the gold. Thus, once the gold leaves the immediate area of production, it is nearly indistinguishable from gold products mined in other areas.

Fact Sheet↗
USGS2017

Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply

Summary Mineral commodities are vital for economic growth, improving the quality of life, providing for national defense, and the overall functioning of modern society. Minerals are being used in larger quantities than ever before and in an increasingly diverse range of applications. With the increasing demand for a considerably more diverse suite of mineral commodities has come renewed recognition that competition and conflict over mineral resources can pose significant risks to the manufacturing industries that depend on them. In addition, production of many mineral commodities has become concentrated in relatively few countries (for example, tungsten, rare-earth elements, and antimony in China; niobium in Brazil; and platinum-group elements in South Africa and Russia), thus increasing the risk for supply disruption owing to political, social, or other factors. At the same time, an increasing awareness of and sensitivity to potential environmental and health issues caused by the mining and processing of many mineral commodities may place additional restrictions on mineral supplies. These factors have led a number of Governments, including the Government of the United States, to attempt to identify those mineral commodities that are viewed as most “critical” to the national economy and (or) security if supplies should be curtailed. This book presents resource and geologic information on the following 23 mineral commodities currently among those viewed as important to the national economy and national security of the United States: antimony (Sb), barite (barium, Ba), beryllium (Be), cobalt (Co), fluorite or fluorspar (fluorine, F), gallium (Ga), germanium (Ge), graphite (carbon, C), hafnium (Hf), indium (In), lithium (Li), manganese (Mn), niobium (Nb), platinum-group elements (PGE), rare-earth elements (REE), rhenium (Re), selenium (Se), tantalum (Ta), tellurium (Te), tin (Sn), titanium (Ti), vanadium (V), and zirconium (Zr). For a number of these commodities—for example, graphite, manganese, niobium, and tantalum—the United States is currently wholly dependent on imports to meet its needs. The first two chapters (A and B) deal with general information pertinent to the study of mineral resources. Chapters C through V describe individual mineral commodities and include an overview of current uses of the commodity, identified resources and their distribution nationally and globally, the state of current geologic knowledge, the potential for finding additional deposits nationally and globally, and geoenvironmental issues that may be related to the production and uses of the commodity. These chapters are updates of the commodity chapters published in 1973 in U.S. Geological Survey Professional Paper 820, “United States Mineral Resources.”

Professional Paper↗
USGS1987

BOREHOLE NEUTRON ACTIVATION: THE RARE EARTHS.

Neutron-induced borehole gamma-ray spectroscopy has been widely used as a geophysical exploration technique by the petroleum industry, but its use for mineral exploration is not as common. Nuclear methods can be applied to mineral exploration, for determining stratigraphy and bed correlations, for mapping ore deposits, and for studying mineral concentration gradients. High-resolution detectors are essential for mineral exploration, and by using them an analysis of the major element concentrations in a borehole can usually be made. A number of economically important elements can be detected at typical ore-grade concentrations using this method. Because of the application of the rare-earth elements to high-temperature superconductors, these elements are examined in detail as an example of how nuclear techniques can be applied to mineral exploration.

IEEE Transactions on Nuclear Science↗
USGS1999

Geological and geophysical setting of the gold-silver vein systems of Unga Island, southwestern Alaska

The topic of this CD-ROM is the geologic framework of gold-silver vein deposits on Unga Island, in the Shumagin Islands, southwestern Alaska. The core of the publication is a new geologic map at a scale of 1:63,360 and aeromagnetic and electromagnetic survey data acquired by industry over the area of mineralization. Both the geologic map as well as a preliminary interpretation of the geophysical data - which are included by permission of the owner - are aimed towards deciphering the relations among volcanism, tectonism, and mineralization. Data and discussions are organized in seven chapters, titles of which are outlined in the table of contents. The chapters consist of viewable text and figure images; postscript versions of the frontispiece figures and all chapter figures are included on the CD-ROM as well. The geologic map is a large viewable figure (Plate 1) that accompanies chapter 2. The map was constructed in ARC and its component coverages are provided in the folder 'Geology' for users who may wish to modify the geologic data or add their own data.

Alaska↗