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USGS2025

Alteration mapping in granitic gneiss using handheld geophysical and geochemical instruments: Implications for iron oxide-apatite and rare earth elements exploration

The Adirondack Mountains of New York, U.S.A. contain iron oxide-apatite (IOA) mineral deposits with variable concentrations of rare earth elements (REE). The IOA mineral deposits are typically hosted in the Lyon Mountain Granite Gneiss and are spatially correlated with extensive Na metasomatism (albitization) of the surrounding country rocks, although some mineral deposits also occur in metagabbro, paragneiss, and anorthosite hosts. The location of albitization zones is key to finding new IOA mineral deposits and better understanding the mineralization processes associated with their genesis. However, the Na alteration zones are generally not visibly identifiable in outcrop or hand specimens because the color and textural changes are subtle and are thus difficult to map. Here, we discuss the results from testing two spectroscopic techniques (handheld, field gamma-ray spectroscopy, and portable X-ray fluorescence (pXRF)) to characterize albitization zones surrounding IOA mineral deposits. The gamma-ray and pXRF spectrometers successfully distinguished the relative intensity of alteration in the Lyon Mountain Granite Gneiss based on the K abundance. The measured K content decreases towards the IOA mineral deposits, and the magnitude and width of the gradient are similar along the strike of each mineral deposit. Elevated Th and U values are present in host rocks adjacent to REE-bearing IOA mineral deposits. The pXRF and gamma-ray spectrometer K values are remarkably consistent with laboratory-based, whole-rock XRF compositional data and, therefore, useful for semi-quantitative analysis. Notably, albitization aureoles are consistent around REE-rich and REE-poor mineral deposits, suggesting that saline fluids are essential for the petrogenesis of IOA mineral deposits but may not be critical to REE mineralization. Ultimately, this study demonstrates the utility of handheld gamma-ray and pXRF spectrometry for identifying otherwise cryptic albitization gradients associated with IOA mineral deposits in granitic gneiss.

New York↗

USGS2013

Book review: Economic geology: Principles and practice: Metals, minerals, coal and hydrocarbons—Introduction to formation and sustainable exploitation of mineral deposits

This volume, available in both hardcover and paperback, is an English translation of the fifth edition of the German language text Mineralische und Energie-Rohstoffe. The book provides an extensive overview of natural resources and societal issues associated with extracting raw materials. The comprehensive list of raw materials discussed includes metals, industrial minerals, coal, and hydrocarbons. The book is divided into four parts: (1) “Metalliferous ore deposits,” (2) “Nonmetallic minerals and rocks,” (3) “Practice of economic geology,” and (4) “Fossil energy raw materials—coal, oil, and gas.” These sections are bound by a brief introduction and an extensive list of up-to-date references as well as an index. Each chapter begins with a concise synopsis and concludes with a summary that contains useful suggestions for additional reading. All figures are grayscale images and line drawings; however, several have been grouped together and reproduced as color plates. Also included is a companion website ( www.wiley.com/go/pohl/geology ) that contains additional resources, such as digital copies of figures, tables, and an expanded index, all available for download in easy-to-use formats. Economic Geology: Principles and Practice: Metals, Minerals, Coal and Hydrocarbons—Introduction to Formation and Sustainable Exploitation of Mineral Deposits. Walter l. Pohl. 2011. Wiley-Blackwell. Pp. 663. ISBN 978-1-4443-3663-4 (paperback).

Economic Geology↗

USGS2006

Metallogeny of the Great Basin: Crustal evolution, fluid flow, and ore deposits

The Great Basin physiographic province in the Western United States contains a diverse assortment of world-class ore deposits. It currently (2006) is the world’s second leading producer of gold, contains large silver and base metal (Cu, Zn, Pb, Mo, W) deposits, a variety of other important metallic (Fe, Ni, Be, REE’s, Hg, PGE) and industrial mineral (diatomite, barite, perlite, kaolinite, gallium) resources, as well as petroleum and geothermal energy resources. Ore deposits are most numerous and largest in size in linear mineral belts with complex geology. U.S. Geological Survey (USGS) scientists are in the final year of a research project initiated in the fall of 2001 to increase understanding of relations between crustal evolution, fluid flow, and ore deposits in the Great Basin. Because of its substantial past and current mineral production, this region has been the focus of numerous investigations over the past century and is the site of ongoing research by industry, academia, and state agencies. A variety of geoinformatic tools was used to organize, reinterpret, and display, in space and time, the large amounts of geologic, geophysical, geochemical, and hydrologic information deemed pertinent to this problem. This information, in combination with concentrated research on (1) critical aspects of the geologic history, (2) an area in northern Nevada that encompasses the major mineral belts, and (3) important mining districts and deposits, is producing new insights about the interplay between key tectonic events, hydrothermal fluid flow, and ore genesis in mineral belts. The results suggest that the Archean to Holocene history of the Great Basin was punctuated by several tectonic events that caused fluids of different origins (sea water, basinal brine, meteoric water, metamorphic water, magmatic water) to move through the crust. Basement faults reactivated during these events localized deformation, sedimentation, magmatism, and hydrothermal fluid flow in overlying rocks to form mineral belts that contain ore deposits of different types and ages that are locally superimposed (demonstrating inheritance). Fluid flow in these systems also was influenced by the distribution of permeable lithologies and paleotopographic highs and lows. Hydrothermal fluids evolved from their initial chemistries towards compositions that reflect the ƒ O 2 and ƒ S 2 buffering capacity of, and the ligands and metals present in, the rocks (±older mineralization) through which they moved. In northern Nevada, where gold deposits are relatively common, carbonaceous, pyritic strata buffered fluids of diverse origins to H 2 S-rich compositions so they could transport gold repeatedly over Paleozoic-Cenozoic time (convergent evolution). Ore formed where metal-laden fluids encountered effective physicochemical traps. Maps of Neogene basin fill and erosion surfaces identify areas where preexisting ore deposits have been progressively exposed or concealed. Comparisons with analogous terrains and deposit types in other parts of the world provide global context. The initial findings and some of the databases, geologic maps, sections, reconstructions, hydrogeologic models, topical syntheses, regional overviews, short courses, field guides, and deposit comparisons produced by project staff and associated managers, contractors, and collaborators have been presented in numerous abstracts, symposia, USGS publications, and professional journals over the last 5 years (see the extensive bibliography). Notable among these was the 2005 Geological Society of Nevada symposium in Reno, Nevada, and the 2005 Geological Society of America annual meeting in Salt Lake City, Utah, where project results were presented to audiences from around the nation and world. The final results of the project will be submitted for publication in 2007 to appropriate USGS and professional journals. A special issue of GEOSPHERE, scheduled for publication in 2007, will be devoted to the results of this project and related work. This special issue will reach an international audience and be available worldwide on the internet. Much of the research for this project has concentrated on areas that will receive the focused attention of the mining industry in the future. As such, the data and interpretations generated by this project have direct use for land-use managers in Federal, State, and local agencies. Improved hydrogeologic models developed by this project will considerably enhance ongoing and future water resource investigations in the region. The increased understanding of when, where, and how hydrothermal systems produce significant economic deposits has direct uses for mineral exploration and for future USGS mineral resource assessments in the Great Basin and other parts of the world.

Great Basin↗

USGS1978

The role of the U.S. Geological Survey in the lithium industry

The U.S. Geological Survey has responsibility in the U.S. Department of the Interior to assess the nation's energy and mineral resources. The evaluation of reserves and resources of a commodity such as lithium should be a continuing process in the light of advancing technology and ever-growing knowledge of its geologic occurrence and geochemical behavior. Although reserves of lithium vary with market demand because of the investment required to find, develop, and appraise an ore body, total resources are a function of the geologic occurrence and geochemical behavior of lithium. By studying known deposits and publishing data on their origin and occurrence, the U.S. Geological Survey can aid in the discovery of new deposits and improve the resource base. Resource data are used both by the government and the private sector. Government funding for research on energy-related technologies such as electric vehicle batteries and fusion power requires assurance that there will be enough lithium available in time for commercialization. Questions of availability for all mineral commodities must be answered by the U.S. Geological Survey so that intelligent decisions can be made.

Energy↗

USGS1999

Environmental setting of the Yellowstone River basin, Montana, North Dakota, and Wyoming

Natural and anthropogenic factors influence water-quality conditions in the Yellowstone River Basin. Physiography parallels the structural geologic setting that is generally composed of several uplifts and structural basins. Contrasts in climate and vegetation reflect topographic controls and the midcontinental location of the study unit. Surface-water hydrology reflects water surpluses in mountainous areas that are dominated by snowmelt runoff, and arid to semiarid conditions in the plains that are dissected by typically irrigated valleys in the remainder of the study unit. Principal shallow aquifers are Tertiary sandstones and unconsolidated Quaternary deposits. Human population, though sparsely distributed in general, is growing most rapidly in a few urban centers and resort areas, mostly in the northwestern part of the basin. Land use is areally dominated by grazing in the basins and plains and economically dominated by mineral-extraction activities. Forests are the dominant land cover in mountainous areas. Cropland is a major land use in principal stream valleys. Water use is dominated by irrigated agriculture overall, but mining and public-supply facilities are major users of ground water. Coal and hydrocarbon production and reserves distinguish the Yellowstone River Basin as a principal energy-minerals resources region. Current metallic ore production or reserves are nationally significant for platinum-group elements and chromium. The study unit was subdivided as an initial environmental stratification for use in designing the National Water-Quality Assessment Program investigation that began in 1997. Ecoregions, geologic groups, mineral-resource areas, and general land-cover and land-use categories were used in combination to define 18 environmental settings in the Yellowstone River Basin. It is expected that these different settings will be reflected in differing water-quality or aquatic-ecological characteristics.

Montana, North Dakota, Wyoming↗

USGS2019

Rare earth elements in coal and coal fly ash

The rare earth elements (REEs) are a group of 17 elements sharing similar chemical properties. They include yttrium (Y, atomic number 39), scandium (Sc, atomic number 21), and the 15 elements of the lanthanide series, atomic numbers 57 (lanthanum, La) to 71 (lutetium, Lu). Because promethium (Pm, atomic number 61) does not occur in the Earth’s crust and scandium typically has different geological occurrences from other REEs, they are not discussed further herein. REEs are, on average, more abundant than precious metals (for example, gold, silver, and platinum), but because of their unique geochemical properties, they do not commonly form economically viable ore deposits. Nevertheless, REEs are increasingly required for a range of modern applications in defense and renewable energy technologies and in commercial products, primarily as magnets, batteries, and catalysts. The United States currently (2018) produces REEs from a single mine in California, accounting for just 9 percent of global production, whereas 70 percent of global REE production comes from China. For these reasons, REEs are considered a critical resource, and the U.S. Geological Survey (USGS) has an interest in helping to identify new sources of REEs for domestic production. In 2017, coal use accounted for about 30 percent of the electric power generated in the United States. Fly ash, produced during the burning of coal, is a fine-grained solid derived from noncombustible constituents of coal, such as clay minerals and quartz. When coal is burned, REEs are retained and enriched in the fly ash and, as a result, fly ash has long been considered a potential resource for REEs. The United States has the world’s largest coal reserves and, even though gas-fired power generation has increased significantly in the last decade, the United States continues to produce vast quantities of fly ash, about half of which is beneficially reused, primarily in construction materials. The remainder is stored, mostly in landfills and impoundments. Thus, annual fly ash production, combined with fly ash already in storage, constitutes a large potential resource. Research into how to utilize coal and coal fly ash as sources of REEs is ongoing. Viable recovery of REEs from coal and coal ash requires identification of coals and ashes with the highest REE concentrations and development of workable methods for REE extraction and recovery. Understanding how REEs occur within fly ash, described in this fact sheet, is one of the keys to developing possible methods for their recovery.

Fact Sheet↗

USGS2026

Geochemical geodatabase of sedimentary strata (coal, coal-adjacent rocks, tuffaceous oil shale, phosphate-rich rocks) and produced water in the Uinta region, Utah and Colorado

The Geochemical Geodatabase of Sedimentary Strata (Coal, Coal-adjacent Rocks, Tuffaceous Oil Shale, Phosphate-rich Rocks) and Produced Water in the Uinta Region, Utah and Colorado, consists of compiled datasets acquired as part of the Carbon Ore, Rare Earth, and Critical Mineral (CORE-CM) Uinta Region assessment funded by the U.S. Department of Energy (DEFE0032046, 2021–2024; Birgenheier et al., 2024). The CORE-CM assessment focused on providing comprehensive geological and geochemical characterization of current and prospective sedimentary-hosted resources including coal, oil shale, phosphatic limestone, and produced water from oil and gas targets present in eastern Utah and northwestern Colorado (Figure 1). This Data Series includes a geodatabase that consists of analytical geochemical data collected September 2021 through December 2024 via portable X-ray fluorescence (pXRF), and laboratory measured analyses produced by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The coal-related geochemical data are derived primarily from the Cretaceous Blackhawk Formation and Ferron Sandstone of Utah, and the Mesaverde Group of Colorado. Additional non-coal resources assessed include oil shale-bearing strata of the Eocene upper Green River Formation (Utah and Colorado), phosphate-rich limestone of the Permian Park City Formation (Utah) and produced water from oil and gas-bearing strata of the Eocene Green River and Wasatch Formations (Uinta Basin) and the Pennsylvanian Paradox Formation (Paradox Basin) (Table 1). The CORE-CM assessment included a wide range of lithologies present in the coal, oil shale, and phosphate geologic resource systems whether or not the specific lithology has current economic value. Geochemical analyses of produced water from oil and gas wells focused on current and emerging hydrocarbon targets in the central Uinta Basin and northern Paradox Basin. A total of 13,092 geochemical analyses from these geologic systems is provided in the included geodatabase. A series of coal quality data (e.g., composition and maceral analyses) is also included in the database and was digitized from archived coal samples from the Utah Geological Survey (Appendix A).

Colorado, Utah↗

USGS1947

Present investigations of radioactive raw materials by the Geological Survey and a recommended program for future work

The Geological Survey's program of investigation of radioactive raw materials is presented herewith under present investigations, plans for future investigations, plan of operation, and cost of operation. This report was prepared at the request of the Atomic Energy Commission. Present investigations are summarized to show the scope of the present Trace Elements program, grouping individual projects into related types of investigations. Plans for future investigations on an expanded scale are outlined. These should provide sufficient data and knowledge of the occurrence and availability of uranium, thorium, and related elements, to permit a more complete evaluation of domestic resources. Reconnaissance projects are designed to discover possible new sources of uranium and thorium and to select areas and materials warranting further investigation. Typical projects leading to the estimation of reserves are the investigation of the carnotite ores of the Colorado Plateau by geologic mapping, exploratory drilling, and related research, and investigation of asphaltic sandstone in Emery County, Utah. Extensive research will be undertaken to establish the principles governing the geological and geochemical relations of uranium, thorium, and associated elements as an essential guide in appraising domestic resources. Particular emphasis will be placed on phosphatic rocks and black shales which offer ultimate resources of uranium far greater than carnotite ores. All the foregoing investigations will be accompanied by chemical, gephysical, and mineralogical research and analytical work. Under plan of operation is discussed the organization of the Trace Elements Unit, space requirements for laboratory and office, the scheduling of investigations, and other related problems. The proposed scheduling of work calls for approximately 109, 173, and 203 man years in fiscal years 1948, 1949, and 1950 respectively. Definite plans have been formulated only for the next three fiscal years, by which time it is assumed the program will reach stable proportions or can be altered as experience dictates. Under cost of operation is set forth the funds available in fiscal year 1947, the status of funds transferred from Atomic Services (14-217/80920), and funds necessary in succeeding fiscal years. The estimate for fiscal year 1948 inclues a non-recurring item of $1,025,000 for establishing adequate laboratories for chemical, physical, spectrographic and mineralogic research and analytical work. The total funds required in fiscal years 1948, 1949, and 1950 to support the proposed program will be $2,440,000, $2,161,000 and $2,198,000 respectively. The Geological survey anticipates contributing from its appropriation in fiscal years 1948, 1949 and 1950 approximately $243,000, $350,000, and $400,000 respectively; the balance of the necessary funds to be contributed by the Atomic Energy Commission in fiscal years 1948, 1949, and 1950 will be approximately $2,196,900, $1,811,000, and $1,798,000 respectively.

Trace Elements Investigations↗

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↗

USGS2020

Mineral deposits of the Mesoproterozoic Midcontinent Rift system in the Lake Superior region – A space and time classification

The Mesoproterozoic Midcontinent Rift System (MRS) of North America hosts a diverse suite of magmatic and hydrothermal mineral deposits in the Lake Superior region where rift rocks are exposed at or near the surface. Historically, hydrothermal deposits, such as Michigan’s native copper deposits and the White Pine sediment-hosted stratiform copper deposit, were major MRS metal producers. On-going exploration for and potential development of copper-nickel sulfide deposits hosted by the Duluth Complex of Minnesota and the opening of the Eagle nickel mine in Michigan indicate an expanding interest in MRS magmatic deposits. MRS hydrothermal and magmatic mineral deposits, many of which are significant past, present, and likely future providers of critical minerals, here are placed into a space and time metallogenic framework. To construct this framework, regional MRS mineral deposits extracted from the U.S. Geological Survey Mineral Resources Data System (MRDS) and the Ontario Ministry of Energy, Northern Development and Mines Mineral Deposit Inventory (MDI) were supplemented by other known and recently recognized mineral deposits described in the literature. All mineral deposits were classified by deposit type, host rock age and type, and estimated timing of mineralization. Deposits were then put into a tectonic evolutionary framework (stages) for the MRS, which shows that deposits formed within discrete spatial and temporal stages of rift evolution.

Lake Superior region↗

USGS2026

Quantitative mineral resource assessment of lithium pegmatite deposits in the northern Appalachian orogen, USA

Lithium demand is projected to increase more than 48 times by 2040 due to electric vehicle production and other energy storage needs. Most lithium production is outside of the USA, thereby increasing supply chain vulnerability. The combined end use importance and heightened supply risk of lithium make this lightest metallic element a critical commodity to the USA. To mitigate this supply risk, the US Geological Survey is actively assessing lithium deposits in the USA. Herein, we detail an assessment for lithium-mineralized pegmatites in the US northern Appalachian Mountains. Permissive tracts were generated by cross-referencing tectonic and geologic maps and mineral occurrence data with mappable criteria derived from generalized and region-specific lithium pegmatite ore deposit models; tracts were then ranked as having high, medium, or low permissibility. Available geophysical and geochemical data were found to be of minimal utility for this deposit type at the scale of the assessment. The number of undiscovered deposits were estimated and integrated into probabilistic simulations, which included an expanded and updated global grade and tonnage model of pegmatite-hosted lithium ore. The estimated total amount of undiscovered resources for the northern Appalachian Orogen has a median value of 1,410,000 metric tons of Li 2 O when considering moderate correlation across sub-regions. At a confidence level of 90%, a resource of at least 90,000 metric tons of Li 2 O remains undiscovered, and at a 10% confidence level, a resource of as much as 7,380,000 metric tons Li 2 O remains undiscovered. After applying an up-to-date economic filter to convert median contained lithium to recoverable material, a correlated total of 900,000 metric tons of Li 2 O may be economically extractable, equating to enough Li 2 O to provide the current annual US lithium supply deficit (presently obtained through net imports) for 127 years at 2025 rates of apparent consumption. This period of provision will inevitably shorten with projected increasing consumption rates, emphasizing that further research could be completed to better delineate regions of high lithium resource potential and support exploration and domestic production.

Connecticut, Delaware, Maine, Massachusetts, New H↗

USGS1956

Host rocks and their alterations as related to uranium-bearing veins in the United States

This paper, dealing with the different kinds of host rocks and their alterations associated with uranium-bearing veins in the United States, is a chapter of a comprehensive report entitled , "Geology of uranium-bearing vein deposits in the United States," in preparation by George W. Walker, Frank W. Osterwald, and others. The comprehensive report will include detailed information on tectonic and structural setting, kinds of host rocks, wall-rock alteration, mineralogy, physical characteristics, processes of deposition, and concepts of origin of uraniferous veins; but, because it will not be completed until sometime in the future, some chapters of the report are being transmitted as they are finished. Part of an introductory chapter to the comprehensive report entitled, "Classification and distribution of uranium-bearing veins in the United States" (Walker and Osterwald, 1956) has already been transmitted; several of the terms used herein are defined in the introductory chapter. Data included in this chapter demonstrate that uranium-bearing veins are: 1) in rocks of nearly all textural, chemical, and mineralogic types; 2) most abundant in holocrystalline, commonly equigranular, igeneous and metamorphic rocks characterized by a moderate to high silica content and and by similar physical properties. Although some of the physiochemical properties of the host rocks are discussed in terms of favorability or nonfavoribility for uranium deposition, the principal purpose of this chapter is to establish the petroloic environment in which uranium-bearing veins have been found. Because favorability or nonfavorability of host rocks is related complexly to the chemistry of ore solutions and to methods or uranium transport and deposition, several hypothetical processes of transport and deposition have been referred to briefly; these and other hypotheses will be outlines and discussed in greater detail in a subsequent chapter. The compilation of data leading to this report and its preparation by a member of the Uranium Research and Resource Section, U.S. Geological Survey, was done on behalf of the Division of Raw Materials, U.S. Atomic Energy Commission. The report is based on both published and unpublished information collected principally by personnel of the U.S. Geological Survey, the U.S. Atomic Energy Commission or its predecessor organization, the Manhattan Engineer District, and to a lesser extent by staff members of other Federal or State agencies and by geologists in private industry. Information concerning foreign uranium-bearing vein deposits has been extracted almost exclusively from published reports; references to these and other data are included at appropriate places.

Trace Elements Investigations↗

USGS2014

Powder X-ray diffraction laboratory, Reston, Virginia

The powder x-ray diffraction (XRD) laboratory is managed jointly by the Eastern Mineral and Environmental Resources and Eastern Energy Resources Science Centers. Laboratory scientists collaborate on a wide variety of research problems involving other U.S. Geological Survey (USGS) science centers and government agencies, universities, and industry. Capabilities include identification and quantification of crystalline and amorphous phases, and crystallographic and atomic structure analysis for a wide variety of sample media. Customized laboratory procedures and analyses commonly are used to characterize non-routine samples including, but not limited to, organic and inorganic components in petroleum source rocks, ore and mine waste, clay minerals, and glassy phases. Procedures can be adapted to meet a variety of research objectives.

Virginia↗

USGS1981

Significant results from using earth observation satellites for mineral and energy resource exploration

A large number of Earth-observation satellites orbit our world several times each day, providing new information about the land and sea surfaces and the overlying thin layer of atmosphere that makes our planet unique. Meteorological satellites have had the longest history of experimental use and most are now considered operational. The geologic information collected by the Landsat, Polar Orbiting Geophysical Observatory (POGO), Magsat, Heat Capacity Mapping Mission (HCMM) and Seasat land and ocean observation systems is being thoroughly tested, and some of these systems are now approaching operational use. Landsat multispectral images provide views of large areas of the Earth under uniform lighting conditions and can be obtained at a variety of scales and formats. Not only do the Landsat data provide highly useful images showing surficial materials and structures such as folds and faults, but also measurements and computer-derived ratios of the brightness of different rock types, alteration zones, and mineral associations. These data have led to the finding of a variety of new ore deposits. In addition, the combination of Landsat digital data and aeromagnetic data has extended the use of Landsat as an exploration tool which can be used to readily relate surface features to subsurface anomalies. Magsat data, now being collected, are helping refine information on major crustal anomalies that were first recognized during the analysis of POGO data. The more nearly circular orbit, lower altitude, and increased sophistication of its vector magnetometer enable Magsat to provide more precise information than POGO. Information of this type is required to develop crustal models. Although Magsat is designed to operate for only 4–8 months, the number of orbits that it should be able to make will be sufficient to accomplish its mission and to record a major magnetic storm expected in 1980. HCMM is a two-band visible to near-IR (0.55–1.1 μm) and thermal infrared (10.2–12.5 μm) system designed to measure reflected solar energy, determine the heat capacity of rocks and to monitor soil moisture, thermal effluents, plant canopy temperatures and snow cover. Launched in April 1978, it is in sun-synchronous, circular orbit at an altitude of 620 km. It is a relatively low-resolution system with an instantaneous field of view (IFOV) of 500–600 m and a swath width of 716 km. However, the system is designed to detect objects in the range of 260°–340° K with a sensitivity (NEδT) of 0.4°K at 280°. Recording the thermal radiation of urban heat islands and high thermal inertia of quartzite strata in the Appalachian region are two examples of its land applications. Launched in June 1978, Seasat operated for only 100 days, but successfully acquired much information over both sea and land. The collection of synthetic aperture radar (SAR) imagery and radar altimetry was particularly important to geologists. Although there are difficulties in processing and distributing these data in a timely manner, initial evaluations indicate that the radar imagery supplements Landsat data by increasing the spectral range and offering a different look angle. The radar altimeter provides accurate profiles over narrow strips of land (1 km wide) and has demonstrated usefulness in measuring icecap surfaces (Greenland, Iceland, and Antarctica). The Salar of Uyuni in southern Bolivia served as a calibration site for the altimeter and has enabled investigators to develop a land-based smoothing algorithm that is believed to increase the accuracy of the system to 10 cm. Data from the altimeter are currently being used to measure subsidence resulting from ground water withdrawal in the Phoenix-Tucson area.

Advances in Space Research↗

USGS1976

Uranium resource assessment in the United States

Uranium is a ubiquitous element-- a little is found in nearly every natural occurring materials, and it is concentrated in many different geologic environments. Thus, uranium differs markedly from the fossil fuels both in its occurrence and how its resources can be assessed. On the one hand uranium behaves like other metals in its occurrences. On the other hand, as a fuel it is like the hydrocarbons in that it is a non-recyclable resources. In addition, uranium occurs in two isotopes that potential may supply energy-- U235 and U238. Present only 0.7% of natural uranium. New technology is being developed to utilize the more abundant isotope U238. Consequently, the U238 obtained from uranium ores that have already been mined and processed (which is now stockpiled) is a resource that may be used in the future.

Conference Paper↗

USGS2013

Chalcopyrite—bearer of a precious, non-precious metal

The mineral chalcopyrite (CuFeS 2 ) is the world's most abundant source of copper, a metal component in virtually every piece of electrical equipment. It is the main copper mineral in several different ore deposit types, the most important of which are porphyry deposits. Chalcopyrite is unstable at the Earth's surface, so it weathers from sulphide outcrops and mine waste piles, contributing acid and dissolved copper to what is known as acid rock drainage. If not prevented, dissolved copper from chalcopyrite weathering will be transported downstream, potentially harming ecosystems along the way. Pristine areas are becoming targets for future copper supply as we strive to meet ever-increasing demands for copper by developed and developing nations. Additionally, our uses for copper are expanding to include technology such as solar energy production. This has lead to the processing of increasingly lower grade ores, which is possible, in part, due to advances in bio-leaching (i.e. metal extraction catalysed by micro-organisms). Although copper is plentiful, it is still a nonrenewable resource. Future copper supply promises to fall short of demand and the volatility of the copper market may continue if we do not prioritize copper use and improve copper recycling and ore extraction efficiency.

Geology Today↗

USGS2015

Critical metals in manganese nodules from the Cook Islands EEZ, abundances and distributions

The Cook Islands (CIs) Exclusive Economic Zone (EEZ) encompasses 1,977,000 km 2 and includes the Penrhyn and Samoa basins abyssal plains where manganese nodules flourish due to the availability of prolific nucleus material, slow sedimentation rates, and strong bottom currents. A group of CIs nodules was analyzed for mineralogical and chemical composition, which include many critical metals not before analyzed for CIs nodules. These nodules have varying sizes and nuclei material; however all are composed predominantly of δ-MnO 2 and X-ray amorphous iron oxyhydroxide. The mineralogy, Fe/Mn ratios, rare earth element contents, and slow growth rates (mean 1.9 mm/10 6 years) reflect formation primarily by hydrogenetic precipitation. The paucity of diagenetic input can be explained by low primary productivity at the surface and resultant low organic matter content in seafloor sediment, producing oxic seafloor and sub-seafloor environments. The nodules contain high mean contents of Co (0.41%), Ni (0.38%), Ti (1.20%), and total rare earth elements plus yttrium (REY; 0.167%), and also high contents of Mo, Nb, V, W, and Zr. Compiled data from a series of four cruises by the Japan International Cooperation Agency and the Mining agency of Japan from 1985 to 2000 were used to generate a map that defines the statistical distribution of nodule abundance throughout the EEZ, except the Manihiki Plateau. The abundance distribution map shows a belt of high nodule abundance (19–45 kg/m 2 ) that starts in the southeast corner of the EEZ, runs northwest, and also bifurcates into a SW trending branch. Small, isolated areas contain abundances of nodules of up to 58 kg/m 2 . Six ~ 20,000 km 2 areas of particularly high abundance were chosen to represent potential exploration areas, and maps for metal concentration were generated to visualize metal distribution and to extrapolate estimated metal tonnages within the six sites and the EEZ as a whole. Grades for Mn, Cu, and Ni are low in CIs nodules in areas of high abundance; however, Ti, Co, and REY show high contents where nodule abundances are high. Of the six areas identified to represent a range of metal contents, one at the northern end of the N-S abundance main belt optimizes the most metals and would yield the highest dry metric tons for Mn (61,002,292), Ni (1,247,834), Mo (186,166), V (356,247), W (30,215), and Zr (195,323). When compared with the Clarion–Clipperton Zone, the CIs nodules show higher nodule abundances (> 25 kg/m 2 over ~ 123,844 km 2 ), and are more enriched in the green-tech, high-tech, and energy metals Co, Ti, Te, Nb, REY, Pt, and Zr. The CIs EEZ shows a significant resource potential for these critical metals due to their high prices, high demand, and the high nodule abundance, which will allow for a smaller footprint for a 20-year mine site and therefore smaller environmental impact.

Ore Geology Reviews↗

USGS1982

Geologic, geochemical and mineral resource potential map of the Piney Creek Wilderness, Stone and Barry counties, Missouri

There is no evidence of significant metallic-mineral deposits in the rock units that are exposed at the surface in the wilderness, but there may be some potential for mineral deposits of two different types at depths from 400ft (120 m) to more than 2,100 ft (640 m) below the surface. Analyses of rock samples from a drill hole 15 mi (24 km) south of the area showed anomalous amounts of several metals in the Derby-Doerun (usage of the Missouri Geological Survey), Potosi, and Eminence Dolomites, which suggests that these units as well as the subsurface Ordovician carbonate units may have a potential for zinc-lead mineralization in the wilderness. Also, a high-amplitude magnetic anomaly along the northwest side of the wilderness suggests a potential for a small to moderate-sized magnetite (iron ore) deposit in the Precambrian basement rocks at a depth of at least 2,100 ft (640 m) below the surface, probably at least partly outside the boundary of the wilderness. In both cases the significance of the potential cannot be evaluated without deep drilling. In the case of the possible magnetite deposit, drilling should be preceded by a detailed magnetic survey to delineate the anomaly more clearly. The wilderness has little potential for resources of industrial minerals because they are readily available elsewhere in the region, and no known potential for energy resources.

Missour↗