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At least 361 records · Page 20Linked to original sources
USGS2011

Summaries of important areas for mineral investment and production opportunities of nonfuel minerals in Afghanistan

The U.S. Geological Survey (USGS) and the U.S. Department of Defense Task Force for Business and Stability Operations (TFBSO) entered into an agreement with the Afghanistan Geological Survey to study and assess the fuel and nonfuel mineral resources of Afghanistan from October 2009 to September 2011 so that these resources could be economically extracted to expand the economy of Afghanistan. This report summarizes the results of joint studies on 24 important areas of interest (AOIs) of nonfuel mineral resources that were identified for mineral investment and production opportunities in Afghanistan. This report is supported by digital data and archival and non-USGS reports on each AOI, and these data are available from the Afghanistan Geological Survey Data Center in Kabul (http://mom.gov.af/en/ and http://www.bgs.ac.uk/afghanminerals/) and for viewing and download on the USGS public Web site and in a separate viewer at http://mapdss2.er.usgs.gov/.

Open-File Report↗
USGS1970

Lead-, zinc-, and barite-bearing samples from the western Brooks Range, Alaska, with a section on petrography and mineralogy

Concentrations of base metal and barite of potential economic significance may be present in the western De Long Mountains, northwestern Alaska. Greater than 2 percent lead and 1 percent zinc were detected semiquantitatively in sulfide-bearing hand samples from one locality, and more than 10 percent lead was analyzed in a related stream sediment sample. The base metals as sulfides, along with barite, have been concentrated in Paleozoic and(or) Mesozoic sedimentary chert. Several other localities at which sulfides appear to be weathering are present within a 100-square-mlle area. Systematic prospecting should determine if the mineralization has regional significance and has resulted in deposits' of possible economic importance.

Alaska↗
USGS2005

Exploration

The worldwide budget for nonferrous, nonfuel mineral exploration was expected to increase by 58 percent in 2004 from the 2003 budget, according to Metals Economics Group (MEG) of Halifax, Nova Scotia. The increase comes two years after a five-year period of declining spending for mineral exploration (1998 to 2002). Figures suggest a subsequent 27 percent increase in budgeted expenditures from 2002 to 2003. For the second consecutive year, all regional exploration budget estimates were anticipated to increase.

Mining Engineering↗
USGS2007

U.S. Geological Survey Mineral Resources Program - Science Supporting Mineral Resource Stewardship

The United States is the world's largest user of mineral resources. We use them to build our homes and cities, fertilize our food crops, and create wealth that allows us to buy goods and services. Individuals rarely use nonfuel mineral resources in their natural state - we buy light bulbs, not the silica, soda ash, lime, coal, salt, tungsten, copper, nickel, molybdenum, iron, manganese, aluminum, and zinc used to convert electricity into light. The USGS Mineral Resources Program (MRP) is the sole Federal source of scientific information and unbiased research on nonfuel mineral potential, production, and consumption, as well as on the environmental effects of minerals. The MRP also provides baseline geochemical, geophysical, and mineral-deposit data used to understand environmental issues related to extraction and use of mineral resources. Understanding how minerals, water, plants, and organisms interact contributes to our understanding of the environment, which is essential for maintaining human and ecosystem health. To support creation of economic and national security policies in a global context, MRP collects and analyzes data on essential mineral commodities from around the world.

Fact Sheet↗
USGS2008

Controls on mineralisation in the Sierra Foothills gold province, central California, USA: A GIS-based reconnaissance prospectivity analysis

The assessment of spatial relationships between the location, abundance and size of orogenic-gold deposits in the highly endowed Sierra Foothills gold province in California, via the combination of field studies and a GIS-based analysis, illustrates the power of such an approach to the characterisation of important parameters of mineral systems, and the prediction of districts likely to host economic mineralisation. Regional- to deposit-scale reconnaissance mapping suggests that deposition of gold-bearing quartz veins occurred in second- and third-order, east-over-west thrusts during regional east - west compression and right-lateral transpression. At the district-scale, significant zones of mineralisation correspond with such transpressional reactivation zones and dilational jogs that developed during the Late Jurassic - Early Cretaceous along the misaligned segments of first-order faults throughout the Sierra Nevada Foothills Metamorphic Belt. Field-based observations and interpretation of GIS data (including solid geology, structural elements, deposit locations, magnetics, gravity) also highlight the importance of structural permeability contrasts, rheological gradients, and variations in fault orientation for localising mineralisation. Although this approach confirms empirical findings and produces promising results at the province scale, enhanced geological, structural, geophysical and geochronological data density is required to generate regionally consistent, high-quality input layers that improve predictive targeting at the goldfield to deposit-scale.

Australian Journal of Earth Sciences↗
USGS1993

International strategic minerals inventory summary report; rare-earth oxides

Bastnaesite, monazite, and xenotime are currently the most important rare-earth minerals. Bastnaesite occurs as a primary mineral in carbonatites. Monazite and xenotime also can be found in primary deposits but are recovered principally from heavy-mineral placers that are mined for titanium or tin. Each of these minerals has a different composition of the 15 rare-earth elements. World resources of economically exploitable rare-earth oxides (REO) are estimated at 93.4 million metric tons in place, composed of 93 percent in primary deposits and 7 percent in placers. The average mineral composition is 83 percent bastnaesite, 13 percent monazite, and 4 percent of 10 other minerals. Annual global production is about 67,000 metric tons of which 41 percent is from placers and 59 percent is from primary deposits; mining methods consist of open pits (94 percent) and dredging (6 percent). This output could be doubled if the operations that do not currently recover rare earths would do so. Resources are more than sufficient to meet the demand for the predictable future. About 52 percent of the world's REO resources are located in China. Ranking of other countries is as follows: Namibia (22 percent), the United States (15 percent), Australia (6 percent), and India (3 percent); the remainder is in several other countries. Conversely, 38 percent of the production is in China, 33 percent in the United States, 12 percent in Australia, and 5 percent each in Malaysia and India. Several other countries, including Brazil, Canada, South Africa, Sri Lanka, and Thailand, make up the remainder. Markets for rare earths are mainly in the metallurgical, magnet, ceramic, electronic, chemical, and optical industries. Rare earths improve the physical and rolling properties of iron and steel and add corrosion resistance and strength to structural members at high temperatures. Samarium and neodymium are used in lightweight, powerful magnets for electric motors. Cerium and yttrium increase the density and heat resistance of sintered ceramics. Yttrium and gadolinium contribute to the efficiency of electronic switches and sensors. Cerium improves the effectiveness of catalysts in the petroleum and automotive industries. Cerium oxides speed glass melting and are used to polish glass by chemical, rather than mechanical, means. Cerium, europium, terbium, and yttrium, as phosphoric compounds, promote the vivid colors of television screens. Consumption of rare earths is expected to grow by about 2.6 percent per year.

Circular↗
USGS1974

Mineral resources of Du Noir Addition, Washakie Wilderness area, Fremont County, Wyoming

The Du Noir Addition to the Washakie Wilderness area consists of 34,200 acres (13,840 hectares) of scenic mountainous terrain that adjoins the Teton Wilderness and Washakie Wilderness areas. The area was studied in 1973 by the U.S. Geological Survey and U.S. Bureau of Mines to evaluate its mineral, fuel, and geothermal energy potential. This evaluation is based on a search of the geologic literature, claim and production records, and fieldwork including mapping, inspection of claims and prospects, interpretation of aeromagnetic maps, and analyses of bedrock and stream-sediment samples. Flat-lying Eocene volcaniclastic rocks of the Absaroka volcanic field are exposed in about two-thirds of the Du Noir Addition. These volcanics unconformably overlie the deeply eroded, northwest-trending Du Noir anticline in which Paleozoic marine strata of Devonian through Permian age are exposed. Of lesser importance are small deposits of Eocene non-volcanic conglomerate, and basaltic intrusive and extrusive rocks of late Pliocene and possibly younger age. The results of this study indicate that the mineral, fuel, and geothermal potential of the Du Noir Addition are minimal. Low-grade copper-molybdenum mineralization occurs outside the addition, associated with intrusive rocks, but no indications of alteration or mineralization were found within the study area. Anomalous, but not economically important, concentrations of molybdenum and uranium were found in Permian and Eocene carbonaceous shales. Phosphate rock in the Phosphoria Formation occurs in beds too thin to constitute a resource. Large amounts of very pure limestone are present in the Madison Limestone, but equally pure limestone, much closer to transportation facilities, is found throughout this part of Wyoming. That part of the Du Noir anticline in the addition is too deeply eroded to be a likely reservoir of oil and gas. Present data indicates a low potential for geothermal energy in or near the addition.

Wyoming↗
USGS2023

Tungsten resources of the northern Rocky Mountains, Montana and Idaho— A synthesis and quantitative assessment of skarn-hosted resources

Mineral resource assessments performed by the U.S. Geological Survey provide a synthesis of available information about the location of known and suspected mineral deposits. This study focuses on skarn-hosted tungsten resources in the northern Rocky Mountain region of east-central Idaho and western Montana which have seen moderate tungsten trioxide production in the past from a variety of mineralization styles including skarn, vein and replacement, and wolframite-quartz veins. The area’s geology is dominated by large Cretaceous and Tertiary plutons that are emplaced into a belt of Mesoproterozoic to Permian sedimentary rock and affected by tectonism related to the Sevier and later Laramide orogenies. Known tungsten skarn mineral sites are associated with contacts between Cretaceous plutons and calcareous and argillaceous sedimentary or metasedimentary rocks, including two skarn deposits in Montana (Calvert and Browns Lake) that are consistent with an updated grade and tonnage model. This study (1) delineates permissive tracts where undiscovered tungsten skarn deposits may occur within 1 kilometer of the surface; (2) presents a tungsten mineral site dataset from a variety of public sources; (3) evaluates currently available geochemical, geophysical, and radiometric age data in support of tract delineation; (4) provides probabilistic estimates of the amount of tungsten and tungsten-mineralized rock that could be contained in undiscovered deposits within one major tract; (5) estimates the value of total undiscovered deposits using economic filter analysis; and (6) provides a synthesis of metallogenic controls on regional tungsten skarn and granitoid-related mineral deposits. Two permissive tracts were delineated: the Great Falls tectonic zone (GFTZ)-Cretaceous tract, for which a quantitative assessment was performed, and the Bitterroot tract, which was assessed in a qualitative manner. The quantitative three-part assessment, conducted in August 2019, indicates that undiscovered tungsten resources might exist in skarn-type deposits within the study area. Using a negative binomial function, a mean of 4 undiscovered deposits was calculated from panel estimates. Simulation results that combine an updated grade and tonnage model with estimates of undiscovered deposits include the amounts of ore and contained tungsten trioxide at different levels of uncertainty. A mean of 250,000 metric tons and median of 200,000 metric tons contained tungsten trioxide was calculated for the undiscovered deposits within the GFTZ-Cretaceous tract. The value of undiscovered deposits was estimated using a new economic filter that considers factors such as mine type, deposit depth, deposit geometry, metallurgical recovery rate, cutoff grade, and tract area. A review of the regional Archean to Paleogene geology suggests that ore metal (copper, molybdenum, and tungsten) variations in intrusion-related deposits of Montana and Idaho may be controlled by a number of factors including the age and composition of underlying basement terranes, depth of emplacement, pluton chemistry and degree of fractionation, redox conditions, and aqueous fluid-melt partition coefficients.

Idaho, Montana↗
USGS2010

Abundances and distribution of minerals and elements in high-alumina coal fly ash from the Jungar Power Plant, Inner Mongolia, China

The fly ash from the Jungar Power Plant, Inner Mongolia, China, is unique because it is highly enriched in alumina (Al 2 O 3 >50%). The fly ash mainly consists of amorphous glass and mullite and trace amounts of corundum, quartz, char, calcite, K-feldspar, clay minerals, and Fe-bearing minerals. The mullite content in fly ash is as high as 37.4% because of high boehmite and kaolinite contents in feed coal. Corundum is a characteristic mineral formed during the combustion of boehmite-rich coal.Samples from the economizer were sieved into six size fractions (<120, 120-160, 160-300, 300-360, 360-500, and >500 mesh) and separated into magnetic, mullite+corundum+quartz (MCQ) and glass phases for mineralogical and chemical analysis. The corundum content increases but amorphous glass decreases with decreasing particle size. Fractions of small particle sizes are relatively high in mullite, probably because mullite was formed from fine clay mineral particles under high-temperature combustion condition. Similarly, fine corundum crystals formed in the boiler from boehmite in feed coal. The magnetic phase consists of hematite, magnetite, magnesioferrite, and MgFeAlO 4 crystals. The MCQ phase is composed of 89% mullite, 6.1% corundum, 4.5% quartz, and 0.5% K-feldspar.Overall, the fly ash from the power plant is significantly enriched in Al 2 O 3 with an average of 51.9%, but poor in SiO 2 , Fe 2 O 3 , CaO, MgO, Na 2 O, P 2 O 5 , and As. Arsenic, TiO 2 , Th, Al 2 O 3 , Bi, La, Ga, Ni, and V are high in mullite, and the magnetic matter is enriched in Fe 2 O 3 , CaO, MnO, TiO 2 , Cs, Co, As, Cd, Ba, Ni, Sb, MgO, Zn, and V. The remaining elements are high in the glass fraction. The concentration of K 2 O, Na 2 O, P 2 O 5 , Nb, Cr, Ta, U, W, Rb, and Ni do not clearly vary with particle size, while SiO 2 and Hg decrease and the remaining elements clearly increase with decreasing particle size. ?? 2009 Elsevier B.V.

International Journal of Coal Geology↗
USGS2015

The Ebola virus disease outbreak and the mineral sectors of Guinea, Liberia, and Sierra Leone

The mineral sector plays a key role in the economies of Guinea, Liberia, and Sierra Leone. The onset of the Ebola virus disease (EVD) outbreak in early 2014, together with changes in mineral market conditions, raised questions regarding the status of mining operations and of mineral development and exploration projects in all three countries. Mineral projects were the underpinnings of World Bank short-term forecasts of increases in gross domestic product (GDP) for all three countries and were expected to be the basis of future economic growth. The significant delay or cancellation of these projects could result in a major economic setback for all three countries. In response to the uncertainty surrounding the status of mineral projects in Guinea, Liberia, and Sierra Leone, the National Minerals Information Center compiled information on the distribution of mines, mineral facilities, and mineral projects under development in the three countries. This fact sheet provides information on the role that the mineral sector plays in their respective economies, on the operating status of mining projects through yearend 2014, and on the coordinated actions by mining companies to support governments and international relief organizations in their efforts to contain the EVD outbreak.

Fact Sheet↗
USGS1999

Environmental models of mineral deposits- A state of the art

Although mineral deposits have been classified by their geologic and mineralogical characteristics for decades, the recognition that mineral deposits also could be classified by their environmental characteristics is relatively new. In the past 5 years, numerous advancements have been made in this subject area, building on the earlier work of economic geologists who classified geologic characteristics. Several different approaches to understanding the environmental behavior of mineral deposits and associated altered areas have been taken, ranging from wholesale assessments of large areas (millions of km 2 ) to detailed assessments of individual watersheds or individual mines. While these first attempts have succeeded in describing some of the environmental characteristics of ore deposits in a number of ways, many important “environmental variables” are not included in present descriptive models. For example, the models should be expanded in scope to include a more thorough treatment of climatic and ecoregional effects- embodying such physical environmental characteristics as precipitation, evaporation, temperature, and ground water-surface water interactions. More complete model descriptions will have applications to the determination of baselines and natural backgrounds in mined and unmined areas, as well as possible anticipated effects of new mining in a given area, and mitigation and remediation strategies. The challenge to geologists and geochemists is to incorporate a widely disparate set of physical and chemical characteristics of mineralized and altered zones at scales ranging from microscopic (sub-millimeter) to macroscopic (10’s to 100’s of kilometers). This paper presents an overview of the development of mineral deposit environmental models, the current state of the art, an evaluation of needed improvements, and expected advancements in this field.

Geologica Hungarica. Series geologica↗
USGS2021

Changes in seabed mining

Chapter 23 of the First World Ocean Assessment (WOA I) focused on marine mining, and particularly on established extractive industries, which are predominantly confined to near-shore areas, where shallow-water, near-shore aggregate and placer deposits, and somewhat deeper water phosphate deposits are found (United Nations, 2017a). At the time of publication, there were no commercially developed deep-water seabed mining (DSM) deposits but an assessment of mining leases and exploration activity was included. Since WOA I, the number of deep-water (depths greater than 200 m below the ocean surface) seabed exploration licenses has increased both within national jurisdictions of coastal, island and archipelagic States, and beyond in the Area (the seabed, ocean floor and subsoil thereof beyond the limits of national jurisdiction) under the administration of the International Seabed Authority (ISA). For the first time, in 2017 deep-water seabed test-mining was carried out by Japan at a water depth of 1,600 m within its exclusive economic zone (EEZ) (METI, 2017). The update in the present Chapter will focus on the nascent deep-water seabed mining industry and mineral deposits. Hereafter, we use seabed for deep-water seabed. Environmental issues focused on impacts from dredging activities and a list of references for some mining operations were provided. However, WOA I could not provide an environmental baseline for DSM and considered that environmental, social and economic aspects were often not adequately understood with available data. Data on potential environmental impacts are still scarce and can differ greatly between mineral extraction from near-shore and seabed mining sites. Information on economic benefits, and to some extent social impacts, of mining is becoming progressively more accessible due to several initiatives promoting an increase in transparency of extractive industries. In 2015, the 2030 Agenda for Sustainable Development was adopted by all United Nations Member States. It includes 17 Sustainable Development Goals (SDGs) to be addressed on the basis of a global partnership. DSM activities may have implications for the achievement of SDGs 1, 5, 7–10, 12–14, and 17.

Book chapter↗
USGS1943

The manganese oxide minerals, a preliminary report

This paper summarizes the results obtained thus far in an intensive study of the manganese oxide minerals. X-ray powder photographs, supplemented by chemical tests, have proved to be the best means for identifying these minerals. Formulas are suggested. Physical properties and X-ray data are listed for the commoner minerals and those for which new data have been obtained. Rules of nomenclature for these minerals are suggested.

Economic Geology↗
USGS1944

The differentiation of magnesite from dolomite in concentrates and tailings

A new method is presented here for differentiating magnesite from dolomite in crushed materials. This method is based on the essentially different temperatures at which these minerals undergo thermal decomposition. The resulting lowly birefringent periclase is easily distinguished microscopically from the highly birefringent dolomite. This method is based on the ease of recognition of the periclase which permits rapid counting and gives reliable quantitative data on mineral composition. A method is given for staining thermally treated specimens for the determination of the distribution of these minerals in rock fragments.

Economic Geology↗
USGS1960

Detrital-appearing uraninite grains in the shinarump member of the chinle formation in northern Arizona

A sample of uranium-bearing conglomerate from the Shinarump member of the Chinle formation in northern Arizona was disaggregated in an ultrasonic separator. The sample, weighing 187 grams, contained about 60 grains of uraninite (from 0.1 to 1 mm diameter) which have the sphericity and polish suggestive of detrital grains . The detrital-appearing grains are associated with abundant interstitial uraninite , sphalerite, and pyrite, which presents conflicting evidence as to the origin of the uranium deposit. No definite conclusions are presented for the occurrence of these grains . However, the evidence strongly suggests that they are probably not detrital in origin, but are uraninite replacements of detrital grains ; the original mineral may have been quartz.

Arizona↗
USGS1971

Coronadite — Modes of occurrence and origin

The lead manganate, "coronadite," was first recognized at the Coronado mine in the Morenci district, Arizona, by Lindgren in 1903. Several years later, the identity of the mineral was questioned and it was not until 1932 that Orcel recognized it in material from Morocco. Since 1955, the mineral has been recognized at numerous places; in the USSR, east of the Ural Mountains, in several districts in Morocco, England, Australia, and India. In recent years, coronadite had been identified at numerous localities in New Mexico, Arizona, Nevada, and California by the writer and others. At this time, it has been identified at 22 localities, and in the opinion of this writer, it will be found at many more places if it is sought for carefully. Author's review of the known occurrences of coronadite and interpretation of the modes of geologic environment show that the mineral is found in veins and hot spring aprons, where it seems to have been deposited by hydrothermal waters from depth and that it is one of the manganese oxide minerals deposited as sediments. Probably it is more widely found in assemblages of minerals of supergene origin.

Arizona, Asturias, California, Chihuahua, Durango,↗
USGS1985

Mineralogy, textures, and relative age relationships of massive sulfide ore in the West Shasta district, California

The Devonian massive sulfide orebodies of the West Shasta district in northern California are composed primarily of pyrite, with lesser amounts of other sulfide and gangue minerals. Examination of polished thin sections of more than 100 samples from the Mammoth, Shasta King, Early Bird, Balaklala, Keystone, and Iron Mountain mines suggests that mineralization may be divided into six paragenetic stages, the last five each separated by an episode of deformation: (1) precipitation of fine-grained, locally colloform and framboidal pyrite and sphalerite; (2) deposition of fine-grained arsenopyrite and coarse-grained pyrite, the latter enclosing tiny inclusions of pyrrhotite; (3) penetration and local replacement of sulfide minerals of stages 1 and 2 along growth zones and fractures by chalcopyrite, sphalerite, galena, ten-nantite, pyrrhotite, bornite, and idaite; (4) recrystallization and remobilization of existing minerals, locally increasing their size and euhedralism and promoting their aggregation; (5) deposition of quartz, white mica, chlorite, and calcite; and (6) formation of bornite, digenite, chalcocite, and covellite during supergene enrichment of several orebodies at the Iron Mountain mine. Despite regional greenschist facies metamorphism and local heating by intrusive bodies, enough of the original depositional features of the ore remain to suggest that the deposits in the district formed by processes similar to those that formed Kuroko- and Besshi-type massive sulfide deposits. Mineralogic and textural evidence do not support a second major episode of massive sulfide mineralization during the Permian.

Economic Geology↗
USGS1987

Interpretation of the regional geochemistry of the Tonopah 1 degree by 2 degrees Quadrangle, Nevada, based on analytical results from stream-sediment and nonmagnetic heavy-mineral-concentrate samples

Results of more than 2,400 analyses of <0.25-mm fraction of stream sediments and nonmagnetic heavy-mineral concentrates from stream sediments from 1,217 sites in the Tonopah quadrangle demonstrate the existence of anomalous concentrations of many metals of economic interest in many areas. Single-element anomalies of As, Pb, or Sb in stream sediment provide general guides to possible mineralization, but multi-element suites are more reliable to characterize types of mineralization. Various combinations of Ag, As, Bi, Cu, Mo, Pb, Sb, and W in stream sediments and concentrates provide guides to five general types of deposits and their geologic environments. Multi-element suites that recur in stream-sediment media resemble those observed in mineralized rock samples, and the distribution of the suites corresponds to the distribution of known types of deposits and to the general geology of the region. Multi-element geochemical anomalies are prominent in the Pilot Mountains, Monte Cristo Range, Paradise Range, Lone Mountain, northeastern Toiyabe Range, Cedar Mountains, and Toquima Range. Strongest multi-element anomalies are associated with plutonic rocks in the western part of the quadrangle. Two base-metal suites are enriched in and around plutons: (1) Bi + W + Pb + Mo ± As, Cu, Sb, a suite that resembles metals enriched in rocks samples from skarn deposits; and (2) Pb + Mo ± As,Cu,Sb, which resembles base-metal enrichments in sulfide vein and replacement deposits, generally associated with intrusions. A third variety of base-metal enrichment that contains Ag is distinguished for its possible economic importance. This Ag-Pb-rich suite occurs both near plutons and in volcanic terrane and generally is near areas of known Ag-rich polymetallic deposits. Many sites are characterized by modest enrichments of two to five elements in the suite As-Mo-Sb-Zn-Ag that resemble enrichments in epithermal ore deposits. Many anomalies of this type are from drainages underlain by Tertiary welded tuff, commonly lacking alteration and mineral prospects. Some of these anomalous sites correlate with areas of known epithermal deposits or siliceous alteration of calcareous rocks, thus this suite may be a guide to precious-metal deposits if there is supporting geologic evidence. The results from regional sampling of stream sediments, utilizing the <0.25-mm fraction and nonmagnetic heavy-mineral-concentrate media, effectively outline most areas of known deposits or alteration in the Tonopah quadrangle. Some clusters of anomalies are larger than the area of known mineral prospects, suggesting that other deposits remain to be discovered. This regional geochemical information is most effective for exploration and resource analysis when integrated with other geologic information, especially rock alteration.

Nevada↗