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USGS2000

Stable isotope systematics of sulfate minerals

Stable isotope studies of sulfate minerals are especially useful for unraveling the geochemical history of geological systems. All sulfate minerals can yield sulfur and oxygen isotope data. Hydrous sulfate minerals, such as gypsum, also yield oxygen and hydrogen isotope data for the water of hydration, and more complex sulfate minerals, such as alunite and jarosite also yield oxygen and hydrogen isotope data from hydroxyl sites. Applications of stable isotope data can be divided into two broad categories: geothermometry and tracer studies. The equilibrium partitioning of stable isotopes between two substances, such as the isotopes of sulfur between barite and pyrite, is a function of temperature. Studies can also use stable isotopes as a tracer to fingerprint various sources of hydrogen, oxygen, and sulfur, and to identify physical and chemical processes such as evaporation of water, mixing of waters, and reduction of sulfate to sulfide. Studies of sulfate minerals range from low-temperature surficial processes associated with the evaporation of seawater to form evaporite deposits to high-temperature magmatic-hydrothermal processes associated with the formation of base-and precious-metal deposits. Studies have been conducted on scales from submicroscopic chemical processes associated with the weathering of pyrite to global processes affecting the sulfur budget of the oceans. Sulfate isotope studies provide important information to investigations of energy and mineral resources, environmental geochemistry, paleoclimates, oceanography (past and present), sedimentary, igneous, and metamorphic processes, Earth systems, geomicrobiology, and hydrology. One of the most important aspects of understanding and interpreting the stable isotope characteristics of sulfate minerals is the complex interplay between equilibrium and kinetic chemical and isotopic processes. With few exceptions, sulfate minerals are precipitated from water or have extensively interacted with water at some time in their history. Because of this nearly ubiquitous association with water, the kinetics of isotopic exchange reactions among dissolved species and solids are fundamental in dictating the isotopic composition of sulfate minerals. In general, the heavier isotope of sulfur is enriched in the higher oxidation state, such that under equilibrium conditions, sulfate minerals (e.g. barite, anhydrite) are expected to be enriched in the heavy isotope relative to disulfide minerals (e.g. pyrite, marcasite), which in turn are expected to be enriched relative to monosulfide minerals (e.g. pyrrhotite, sphalerite, galena) ( Sakai 1968 , Bachinski 1969 ). The kinetics of isotopic exchange among minerals with sulfur at the same oxidation state, such as sphalerite, and galena, are such that equilibrium is commonly observed. In contrast, isotopic equilibrium for exchange reactions between minerals of different oxidation states depends on factors such as the pH, time and temperature of reaction, the direction of reaction, fluid composition, and the presence or absence of catalysts ( Ohmoto and Lasaga 1982 ). The kinetics of oxygen isotope exchange between dissolved sulfate and water are extremely sluggish. Extrapolation of the high-temperature (100 to 300°C) isotopic exchange kinetic data of Chiba and Sakai (1985) to ambient temperatures suggests that it would take several billions of years for dissolved sulfate and seawater to reach oxygen isotopic equilibrium. In contrast, the residence time of sulfate in the oceans is only 7.9 million years ( Holland 1978 ). However, at higher temperatures (>200°C), oxygen isotopic exchange is sufficiently rapid to permit application of sulfate isotope geothermometry to geothermal systems and hydrothermal mineral deposits. In general, equilibrium prevails at low pH and high temperatures, whereas kinetic factors preclude equilibrium at low temperatures even at low pH. Thus, the sluggish kinetics of sulfur and oxygen isotope exchange reaction at low temperatures impair the use of these isotopes to understand the conditions of formation of sulfate minerals in these environments. However, because of these slow kinetics, the oxygen and sulfur isotopic compositions of sulfate minerals may preserve a record of the sources and processes that initially produced the dissolved sulfate, because the isotope ratios may not re-equilibrate during fluid transport and mineral precipitation. The first part of this chapter is designed to provide the reader with a basic understanding of the principles that form the foundations of stable isotope geochemistry. Next, an overview of analytical methods used to determine the stable isotope composition of sulfate minerals is presented. This overview is followed by a discussion of geochemical processes that determine the stable isotope characteristics of sulfate minerals and related compounds. The chapter then concludes with an examination of the stable isotope systematics of sulfate minerals in a variety of geochemical environments.

Reviews in Mineralogy and Geochemistry↗

USGS2022

Alaska focus area definition for data acquisition for potential domestic sources of critical minerals in Alaska for antimony, barite, beryllium, chromium, fluorspar, hafnium, magnesium, manganese, uranium, vanadium, and zirconium

Phase 3 of the Earth Mapping Resources Initiative (Earth MRI) focuses on geologic belts that are favorable for hosting mineral systems that could contain the critical minerals antimony, barite, beryllium, chromium, fluorspar, hafnium, magnesium, manganese, uranium, vanadium, and zirconium. Prior phases of the Earth MRI program in Alaska focused only on rare earth elements, aluminum, cobalt, graphite, lithium, niobium, platinum-group metals, tantalum, tin, titanium, and tungsten. An additional 11 critical minerals planed for future phases of Earth MRI (As, Bi, Cs, Ga, Ge, In, Re, Rb, Sc, Sr, Te) are considered prospective in these focus areas. Together, Alaska focus areas address 22 of the 35 minerals or mineral material groups presently deemed critical. This report describes the methodology and techniques utilized to define focus areas for future data acquisition in Alaska; the conterminous United States are covered in a separate report. Focus areas are identified using a mineral systems framework, which accounts for all the possible tectonic and geologic settings where co-genetic mineral deposits may form. These deposits contain many commodities, including byproduct and critical minerals. Large system-scale processes may be evaluated using such a framework to determine the influence they play on critical mineral endowment within the deposits. Analyzing larger mineral systems provides an integrated and broad context to determine how and where critical minerals are sourced, transported, and deposited in geologic systems. Statewide geological, geochemical, geophysical, and mineral occurrence datasets informed the delineation of focus areas in Alaska. For some mineral systems, previously published data-driven prospectivity analyses for critical mineral-bearing deposit types provided the basis for focus areas. We report a total of 22 new focus areas that are prospective for phase 3 critical minerals. These new focus areas represent four different mineral systems that are known or suspected to occur in Alaska. An additional 55 focus areas that were previously identified for phase 1 and phase 2 commodities were also identified as being prospective for phase 3 critical minerals. Collectively, 102 focus areas in Alaska have known or suspected potential for hosting phase 1, phase 2, and (or) phase 3 critical minerals. These focus areas represent 17 different mineral systems also containing critical minerals that are planned for consideration in future Earth MRI phases. Thus, the focus areas delineated herein, and in previous reports for Alaska, are comprehensive for all critical minerals as presently defined and may be used to guide the collection of new geologic, geochemical, and geophysical data in the region.

Alaska↗

USGS2016

Discharge, water temperature, and water quality of Warm Mineral Springs, Sarasota County, Florida: A retrospective analysis

Warm Mineral Springs, located in southern Sarasota County, Florida, is a warm, highly mineralized, inland spring. Since 1946, a bathing spa has been in operation at the spring, attracting vacationers and health enthusiasts. During the winter months, the warm water attracts manatees to the adjoining spring run and provides vital habitat for these mammals. Well-preserved late Pleistocene to early Holocene-age human and animal bones, artifacts, and plant remains have been found in and around the spring, and indicate the surrounding sinkhole formed more than 12,000 years ago. The spring is a multiuse resource of hydrologic importance, ecological and archeological significance, and economic value to the community. The pool of Warm Mineral Springs has a circular shape that reflects its origin as a sinkhole. The pool measures about 240 feet in diameter at the surface and has a maximum depth of about 205 feet. The sinkhole developed in the sand, clay, and dolostone of the Arcadia Formation of the Miocene-age to Oligocene-age Hawthorn Group. Underlying the Hawthorn Group are Oligocene-age to Eocene-age limestones and dolostones, including the Suwannee Limestone, Ocala Limestone, and Avon Park Formation. Mineralized groundwater, under artesian pressure in the underlying aquifers, fills the remnant sink, and the overflow discharges into Warm Mineral Springs Creek, to Salt Creek, and subsequently into the Myakka River. Aquifers described in the vicinity of Warm Mineral Springs include the surficial aquifer system, the intermediate aquifer system within the Hawthorn Group, and the Upper Floridan aquifer in the Suwannee Limestone, Ocala Limestone, and Avon Park Formation. The Hawthorn Group acts as an upper confining unit of the Upper Floridan aquifer. Groundwater flow paths are inferred from the configuration of the potentiometric surface of the Upper Floridan aquifer for September 2010. Groundwater flow models indicate the downward flow of water into the Upper Floridan aquifer in inland areas, and upward flow toward the surface in coastal areas, such as at Warm Mineral Springs. Warm Mineral Springs is located in a discharge area. Changes in water use in the region have affected the potentiometric surface of the Upper Floridan aquifer. Historical increase in groundwater withdrawals resulted in a 10- to 20-foot regional decline in the potentiometric surface of the Upper Floridan aquifer by May 1975 relative to predevelopment levels and remained at approximately that level in May 2007 in the area of Warm Mineral Springs. Discharge measurements at Warm Mineral Springs (1942–2014) decreased from about 11–12 cubic feet per second in the 1940s to about 6–9 cubic feet per second in the 1970s and remained at about that level for the remainder of the period of record. Similarity of changes in regional water use and discharge at Warm Mineral Springs indicates that basin-scale changes to the groundwater system have affected discharge at Warm Mineral Springs. Water temperature had no significant trend in temperature over the period of record, 1943–2015, and outliers were identified in the data that might indicate inconsistencies in measurement methods or locations. Within the regional groundwater basin, Warm Mineral Springs is influenced by deep Upper Floridan aquifer flow paths that discharge toward the coast. Associated with these flow paths, the groundwater temperatures increase with depth and toward the coast. Multiple lines of evidence indicate that a source of warm groundwater to Warm Mineral Springs is likely the permeable zone of the Avon Park Formation within the Upper Floridan aquifer at a depth of about 1,400 to 1,600 feet, or deeper sources. The permeable zone contains saline groundwater with water temperatures of at least 95 degrees Fahrenheit. The water quality of Warm Mineral Springs, when compared with other springs in Florida had the highest temperature and the greatest mineralized content. Warm Mineral Springs water is characterized by a slight-green color, with varying water clarity, low dissolved oxygen (indicative of deep groundwater), and a hydrogen sulfide odor. Water-quality samples detected ammonium-nitrogen and nitrates, but at low concentrations. The drinking water standard for nitrate adopted by the U.S. Environmental Protection Agency is 10 milligrams per liter, measured as nitrogen. Water samples collected at spring vents by divers on April 29, 2015, had concentrations of 0.9 milligram per liter nitrate-nitrogen at vent A and 0.04–0.05 milligram per liter at vents B, C, and D. Typically, the water clarity is highest in the morning (about 30 feet Secchi depth) and often decreases throughout the day. Analysis of existing data provided some insight into the hydrologic processes affecting Warm Mineral Springs; however, data have been sparsely and discontinuously collected since the 1940s. Continuous monitoring of hydrologic characteristics such as discharge, water temperature, specific conductance, and water-quality indicators, such as nitrate and turbidity (water clarity), would be valuable for monitoring and development of models of spring discharge and water quality. In addition, water samples could be analyzed for isotopic tracers, such as strontium, and the results used to identify and quantify the sources of groundwater that discharge at Warm Mineral Springs. Groundwater flow/transport models could be used to evaluate the sensitivity of the quality and quantity of water flowing from Warm Mineral Springs to changes in climate, aquifer levels, and water use.

Florida↗

USGS2020

Focus areas for data acquisition for potential domestic resources of 11 critical minerals in the conterminous United States, Hawaii, and Puerto Rico—Aluminum, cobalt, graphite, lithium, niobium, platinum-group elements, rare earth elements, tantalum, tin, titanium, and tungsten

In response to a need for information on potential domestic sources of critical minerals, the Earth Mapping Resources Initiative (Earth MRI) was established to identify and prioritize areas for acquisition of new geologic mapping, geophysical data, and elevation data to improve our knowledge of the geologic framework of the United States. Phase 1 of Earth MRI concentrated on those geologic terranes favorable for hosting the rare earth elements (REEs). Phase 2 continued to address the REEs and also identified focus areas for potential domestic sources of 10 more of the 35 critical minerals on the U.S. critical minerals list (aluminum, cobalt, graphite, lithium, niobium, platinum-group elements, tantalum, tin, titanium, tungsten). This report describes the methodology, data sources, and summary results for mineral systems that host these 11 critical minerals in the conterminous United States, Hawaii, and Puerto Rico; Alaska is covered in a separate report. The mineral systems framework adopted for this study links critical mineral commodities to families of genetically related mineral deposit types. The mineral systems approach is an efficient approach, providing a simultaneous evaluation of geologic terranes through aggregation of genetically related mineral deposit types that are much larger than individual ore deposits. Geologic, geochemical, topographic, and geophysical mapping provided by Earth MRI will document geologic features that reflect the extent of individual mineral systems and provide information about critical mineral deposits that may not have been recognized previously. Each critical mineral commodity is discussed in terms of importance to the Nation’s economy, modes of occurrence, mineral systems, and deposit types along with maps and tables listing examples of focus areas for each critical mineral. Important mineral systems for these critical minerals include chemical weathering systems for aluminum (bauxite); placer systems for titanium and REEs; metamorphic systems for graphite; mafic magmatic systems for platinum-group elements and cobalt; lacustrine evaporite and porphyry tin systems for lithium; and copper-molybdenum-gold (Cu-Mo-Au) systems for tungsten. REEs occur in many different mineral systems. Focus areas were developed by scientists from the U.S. Geological Survey in collaboration with scientists from State geological surveys and other institutions. This first national-scale compilation of focus areas represents an initial step in addressing the Nation’s critical mineral needs by screening areas for acquisition of new data to provide the geologic framework necessary for identifying domestic sources of critical minerals.

Open-File Report↗

USGS2026

The mineral chemistry networks of tin and tungsten reflect metallogenic eras of the Mesozoic

Continental remobilization is a crucial driver of metallogenesis and the formation of ore deposits. Some of the world’s largest mineral deposits of the economically valuable elements tin (Sn), tungsten (W), gold (Au), copper (Cu), lead (Pb), and zinc (Zn) formed during the Mesozoic Era. Additionally, the chemistry and distribution of the elements Sn and W have been investigated in previous studies to understand planetary formation and differentiation processes. These two elements are largely co-located during certain South China Mesozoic metallogenic events but are not co-located during other time periods in the same regions. Here, we investigated the mineral chemistry network similarities and dissimilarities of Sn and W to understand their mineral formation and distribution during the Mesozoic Era and throughout Earth history. Mineral chemistry network community detection analysis and electronegativity associations among mineral constituent elements of Sn minerals and W minerals indicate that the elements have similar chemistry among their oxide minerals. However, Sn forms a much wider range of minerals that also contain S compared to W, which occurs in a limited number of S-containing minerals. The divergent constituent element interactions among S-containing Sn minerals and W minerals reflect the redox sensitivity and importance of oxygen (O) fugacity in Sn mineral formation. Conversely, extensive W mineral deposits are known to form at both high and low O fugacities. The similarities and differences between the mineral chemistry networks of Sn and W reflect the mineral distribution of the two elements in the Sn-W mineralization event from 160 to 139 Ma vs. the Sn–uranium (U) mineralization event from 125 to 98 million years ago (Ma). The mineral chemistry and distribution of Mesozoic Sn and W deposits illustrate the contrasting importance of redox and O fugacity on the mineral formation of different elements, and the dynamic crustal evolution that took place during this period of Earth history.

Geosciences↗

USGS2010

Mineral Commodity Summaries 2010

Each chapter of the 2010 edition of the U.S. Geological Survey (USGS) Mineral Commodity Summaries (MCS) includes information on events, trends, and issues for each mineral commodity as well as discussions and tabular presentations on domestic industry structure, Government programs, tariffs, 5-year salient statistics, and world production and resources. The MCS is the earliest comprehensive source of 2009 mineral production data for the world. More than 90 individual minerals and materials are covered by two-page synopses. For mineral commodities for which there is a Government stockpile, detailed information concerning the stockpile status is included in the two-page synopsis. National reserves information for most mineral commodities found in this report, including those for the United States, are derived from a variety of sources. The ideal source of such information would be comprehensive evaluations that apply the same criteria to deposits in different geographic areas and report the results by country. In the absence of such evaluations, national reserves estimates compiled by countries for selected mineral commodities are a primary source of national reserves information. Lacking national assessment information by governments, sources such as academic articles, company reports, presentations by company representatives, and trade journal articles, or a combination of these, serve as the basis for national reserves information reported in the mineral commodity sections of this publication. A national estimate may be assembled from the following: historically reported reserves information carried for years without alteration because no new information is available; historically reported reserves reduced by the amount of historical production; and company reported reserves. International minerals availability studies conducted by the U.S. Bureau of Mines (USBM), before 1996, and estimates of identified resources by an international collaborative effort (the International Strategic Minerals Inventory) are the basis for some reserves estimates. The USGS collects information about the quantity and quality of mineral resources but does not directly measure reserves, and companies or governments do not directly report reserves to the USGS. Reassessment of reserves is a continuing process, and the intensity of this process differs for mineral commodities, countries, and time period. Throughout the history of Mineral Commodity Summaries and its predecessor prior to 1978, Commodity Data Summaries, the presentation of resource data has evolved. Although world resources have been discussed each year, presentation of reserves and reserve base data varied. From 1957 through 1979, only reserves information was published in the reports, but from 1980 through 1987, only estimates of reserve base, a concept introduced by the U.S. Bureau of Mines (USBM) and the USGS in 1980, were published. Beginning in 1988, both reserves and reserve base information were listed for each mineral commodity where applicable and available. Prior to 1996, the minerals availability studies conducted by the USBM and work with international collaborators were the basis for reserve base data reported in Mineral Commodity Summaries. When the USBM was closed in 1996, this function was discontinued. Since that time, reserve base estimates have been updated to be consistent with changes in reserves, but the nonreserves component of the information upon which the reserve base data were estimated is not current enough to support defensible reserve base estimates. For that reason, publication of reserve base estimates was discontinued for Mineral Commodity Summaries 2010. Abbreviations and units of measure, and definitions of selected terms used in the report, are in Appendix A and Appendix B, respectively. A resource/reserve classification for minerals, based on USGS Circular 831 (published with the U.S. Bureau of Mines) is Appendix C, and a directory of USGS minerals information country specialists and their responsibilities is Appendix D. The USGS continually strives to improve the value of its publications to users. Constructive comments and suggestions by readers of the MCS 2010 are welcomed.

Mineral Commodity Summaries↗

USGS2022

Mineral sources and transport pathways for arsenic release in a coastal watershed, USA

Metasedimentary bedrock of coastal Maine contains a diverse suite of As-bearing minerals that act as significant sources of elements found in ground and surface waters in the region. Arsenic sources in the Penobscot Formation include, in order of decreasing As content by weight: löllingite and realgar ( c. 70%), arsenopyrite, cobaltite, glaucodot, and gersdorffite (in the range of 34–45%), arsenian pyrite (<4%), and pyrrhotite (<0.15%). In the Penobscot Formation, the relative stability of primary As-bearing minerals follows a pattern where the most commonly observed highly altered minerals are pyrrhotite, realgar, niccolite, löllingite > glaucodot, arsenopyrite-cobaltian > arsenopyrite, cobaltite, gersdorffite, fine-grained pyrite, Ni-pyrite > coarse-grained pyrite. Reactions illustrate that oxidation of Fe-As disulphide group and As-sulphide minerals is the primary release process for As. Liberation of As by carbonation of realgar and orpiment in contact with high-pH groundwaters may contribute locally to elevated contents of As in groundwater, especially where As is decoupled from Fe. Released metals are sequestered in secondary minerals by sorption or by incorporation in crystal structures. Secondary minerals acting as intermediate As reservoirs include claudetite ( c. 75%), orpiment (61%), scorodite ( c. 45%), secondary arsenopyrite ( c. 46%), goethite (<4490 ppm), natrojarosite (<42 ppm), rosenite, melanterite, ferrihydrite, and Mn-hydroxide coatings. Some soils also contain Fe-Co-Ni-arsenate, Ca-arsenate, and carbonate minerals. Reductive dissolution of Fe-oxide minerals may govern the ultimate release of iron and arsenic – especially As(V) – to groundwater; however, dissolution of claudetite (arsenic trioxide) may directly contribute As(III). Processes thought to explain the release of As from minerals in bedrock include oxidation of arsenian pyrite or arsenopyrite, or carbonation of As-sulphides, and most models based on these generally rely on discrete minerals or on a fairly limited series of minerals. In contrast, in the Penobscot Formation and other metasedimentary rocks of coastal Maine, oxidation of As-bearing Fe-cobalt-nickel-sulphide minerals, dissolution (by reduction) of As-bearing secondary As and Fe hydroxide and sulphate minerals, carbonation and/or oxidation of As-sulphide minerals, and desorption of As from Fe-hydroxide mineral surfaces are all thought to be involved. All of these processes contribute to the occurrence of As in groundwaters in coastal Maine, as a result of variability in composition and in stability of the As source minerals. Arsenic contents of soils and groundwater thus reflect the predominant influence and integration of a spectrum of primary mineral reservoirs (instead of single or unique mineral reservoirs). Cycling of As through metasedimentary bedrock aquifers may therefore depend on consecutive stages of carbonation, oxidation and reductive dissolution of primary and secondary As host minerals.

Maine↗

USGS1971

A heavy mineral study of Pleistocene and Holocene sediments near Nome, Alaska

A heavy mineral study was carried out for sand-size fractions of onshore Holocene sediments (modern beach and river sediments), nearshore Holocene and Pleistocene relict sediments, and Pleistocene and Pliocene sediments from several nearshore drill-holes. Heavy mineral assemblages of these sediments are dominated by garnet, chlorite, epidote, chloritoid, sphene, and staurolite. The nearshore region of Nome is mainly underlain by various types of Pleistocene sediments such as relict gravel that Mantles glacial drift, relict gravel over Nome River outwash fan, relict gravelly sand of submerged beaches, and relict gravel that mantles bedrock. In places these relict sediments are covered by Holocene sandy and muddy sediments. The high concentration of heavy minerals is expected for various relict sediments, because the latter were winnowed by several transgressions and regressions of the sea during Pleistocene time. Concentration of heavy minerals, however, is greater for Holocene sand than relict gravel, which mantles glacial drift and relict gravelly sand of submerged beaches. The high concentration of heavy minerals in Holocene sand suggests the winnowing of sand by strong bottom currents. The low concentration of heavy minerals in the relict gravel on glacial drift and relict gravelly sand of submerged beaches is probably due to the heterogenous nature of relict sediments. Sand fractions of the relict sediments probably have been introduced during the Holocene time. Also, contamination of samples of relict gravel from underlying glacial drift is suspected. A greater concentration of coarse gold particles (1 iiuii. or larger) is found in nearshore relict gravel that mantles glacial drift than in any other sediment type. Relict gravel on glacial drift, which carries high gold values, does not show a high concentration of heavy minerals or a high concentration of garnet. Two factors account for the lack of correlation between concentration of gold and the other heavy minerals: (1) contrast between hydraulic properties of the gold particles and other heavy minerals, and (2) the heterogeneous nature of relict sediments. Because of their extremely high specific gravity, coarse gold particles are not moved by longshore currents or bottom currents from relict gravel which mantles glacial drift, whereas the heavy minerals which are mostly medium to fine sand in size, are transported by longshore currents and strong bottom currents. The Holocene sand winnowed by strong bottom currents shows a high concentration of heavy minerals. Heavy mineral assemblages are more or less similar for the various sediments. Minor compositional variations mainly reflect the effect of sorting of mineral grains according to size and specific gravity. The frequencies of garnet and staurolite are slightly higher than average for modern beach and river sediments. In nearshore sediments, garnet is most abundant in Holocene sand winnowed by strong bottom currents. Holocene silty sediment which occurs in small patches is characterized by high concentration of micaceous minerals and low concentration of garnet, because the weak currents which deposit fine sediments usually carry light micaceous minerals in great abundance and minerals of high specific gravity like garnet in small amounts. Samples of Pleistocene glacial till and Pliocene marine silt from several nearshore drill-hole locations show high concentrations of micaceous minerals and low concentration of garnet. Holocene, Pleistocene, and Pliocene sediments of Nome are mostly derived from the same general metamorphic source rocks of the inland region. The majority of the minerals found in heavy mineral assemblages, such as garnet, chlorite, epidote, chloritoid, sphene, staurolite, hornblende, and tremolite-actinolite, are reported to occur in the metamorphic rocks of Nome and the adjacent region.

Alaska↗

USGS2023

Critical minerals in subduction-related magmatic-hydrothermal systems of the United States

During the World War and Cold War eras (1910s–1990s), domestic consumption of numerous mineral commodities relied increasingly on imported supplies. Consumption reliance has since expanded to include 50 “critical minerals” (elements and mineral commodities) that are mostly to entirely imported and subject to curtailment by suppliers or supply chain disruption. New domestic supplies of critical minerals are being pursued by mining companies and by several federal departments and agencies. Information on domestic deposits and resources of critical minerals is being compiled by the U.S. Geological Survey Mineral Resources Program, which has organized investigations by mineral system, deposit type, and commodity. Production, reserves, resources, and inventories of 21 critical minerals in domestic magmatic-hydrothermal deposits related to subduction-generated magmatism, and in tailings, slag, slimes, and electrolyte from copper concentrators, smelters, and refineries that processed some deposits, are largely restricted to Western States and Alaska. The critical mineral commodities Al, Sb, As, Bi, Co, fluorite, Ga, Ge, In, Mn, Ni, Nb, Pd, Pt, potash, Re, Ta, Te, Sn, W, and V are variably concentrated in porphyry/skarn copper-(molybdenum), skarn-replacement-vein (S-R-V) tungsten, polymetallic sulfide S-R-V intermediate sulfidation (IS), high-sulfidation gold-silver, low-sulfidation gold-silver, and lithocap alunite deposit types. These deposit types occur in porphyry copper-molybdenum-gold, alkalic porphyry, porphyry tin (granite related), and reduced intrusion-related mineral systems. Production, reserves, and resources of Co, Ni, Nb, Pd, Pt, Ta, Sn, and V in subduction-related deposits in Western States are insignificant to small, mostly equivalent to months to a few years of recent annual domestic consumption (2016–2020). Significant inventories, equivalent to 2 or more years of consumption of aluminum, antimony, potash, and tungsten in unmined S-R-V tungsten, polymetallic sulfide S-R-V-IS, and lithocap alunite deposits vary from approximately 2 to 8 years. Several decades of consumption of arsenic, bismuth, fluorite, gallium, germanium, and indium exist in some polymetallic sulfide S-R-V-IS and lithocap alunite deposit types. Based on concentrations of critical minerals in reserves, resources, drill holes, and deposit domains (ore types), and in captive refinery records, the largest domestic inventories of Sb, As, Bi, Re, and Te, and possibly Ga, Ge, In, Sn, and W, are in porphyry copper-molybdenum (Cu-Mo) deposits in Alaska, Idaho, Utah, and Arizona, and in interim products of processing porphyry Cu-Mo deposit ores for recovery of copper and molybdenum. Concentrations of critical minerals in archival specimens and sample collections, although somewhat biased by collection and conservation decisions and categorization, are broadly proportionate to those in reserves, resources, and drill holes. These concentrations imply significant inventories of some critical minerals in deposits for which production, resources, and refinery records are unavailable or incomplete. Because of the large masses of ores mined and processed annually (hundreds of millions of metric tons) and in reserves and resources (hundreds of millions of metric tons to billions of metric tons), calculated inventories of critical minerals in porphyry Cu-Mo deposits are equivalent to decades and centuries of recent consumption. However, these inventories should not be considered consumable supplies without reserve definition and development of economically viable mining plans and recovery techniques. An expeditious strategy for elimination or reduction of import reliance is recovery, and improved recovery efficiency, of Sb, As, Bi, Re, and Te, and possibly Ga, Ge, In, Ni, Sn, Ti, and W; during concentration and refining of copper and molybdenum minerals in ores of operating porphyry Cu-Mo mines; and in unmined porphyry Cu-Mo resources. These chalcophile, siderophile, and lithophile critical minerals, often undetectable in ore, are concentrated (hundreds of parts per million to percents) in slimes and electrolyte during copper electrorefining or could be recovered, in part, during sulfide concentration and smelting. Other than rhenium (recovered during molybdenum refining) and tellurium, all have been routinely discarded. Subsidization (for example, commodity price guarantees, tax credits, recovery technology development), political initiative, and (or) sustained market favorability could support new production of critical mineral commodities from subduction-related magmatic-hydrothermal deposits in Western States. In addition, insufficient domestic refining capacity could relegate the large inventories of critical minerals in porphyry Cu-Mo reserves and resources (for example, Pebble, Alaska; Resolution and Copper World [Rosemont], Arizona) to exportation in concentrates and importation insecurity, fortifying their present status.

Scientific Investigations Report↗

USGS1959

Ion exchange in clays and other minerals

Ion exchange in clays and other minerals is dependent on the crystalline structure of the mineral and on the chemical composition of any solution in contact with the mineral. The structures of clay minerals and zeolites are briefly described to provide a background for the discussion of their ion-exchange reactions. Ion exchange in these minerals is a reversible chemical reaction that takes place between ions held near a mineral surface by unbalanced electrical charges within the mineral framework and ions in a solution in contact with the mineral. Generally the excess charge on the mineral is negative, and it attracts cations from the solution to neutralize this charge. The chemical reactions in ion exchange follow the law of mass action, but the reactions are restricted by the number of exchange sites on the mineral and by the strength of the bonding of the exchangeable cations to the mineral surface. Titration of H-clays with bases shows that montmorillonites and "illites" behave like a mixture of two or three different acids, whereas kaolinite, with an indefinite number of exchange sites, behaves like an indefinite number of acids. Ion-exchange capacity is measured in chemical equivalents of base adsorbed at pH 7. Each clay mineral has a range of exchange capacities because of differences in structure and in chemical composition. The ranges (in milliequivalents per 100 grams) are kaolinite, 3-15; halloysite (2H 2 O), 5-10; halloysite (4H 2 O), 40-50; montmorillonite, 70-100; "illite," 10-40; vermiculite, 100-150; glauconite, 11-20; attapulgite, 20-30; and allophane, 70. The common metallic cations found in exchange positions in clay minerals are Ca +2 , Mg +2 , Na + , and K + . At low pH values H + replaces other cations. The order of replaceability of the common cations has been found to be: Li + < Na + < K + < Rb + < Cs + and Mg +2 < Ca+2 < Sr +2 < Ba +2 Bivalent cations enter the exchange sites preferentially to univalent cations. The common exchangeable cation in most clay minerals in soils is Ca +2 . Other exchange phenomena discussed are anion exchange, fixation of cations and anions by clay minerals, effect of environment on cation exchange, and the exchange capacity of zeolites, of rocks, of other minerals, of organic matter and organic complexes, and of amorphous mineral material.

GSA Bulletin↗

USGS2015

Development, evolution, and destruction of the saline mineral area of Eocene Lake Uinta, Piceance Basin, western Colorado

Halite and the sodium bicarbonate mineral nahcolite were deposited in Eocene-age saline Lake Uinta in the Piceance Basin, northwestern Colorado. Variations in the areal extent of saline mineral deposition through time were studied using descriptions of core and outcrop. Saline minerals have been extensively leached by groundwater, and the original extent of saline deposition was determined from the distribution of empty vugs and collapse breccias. Because vugs and breccias strongly influence groundwater movement, determining where leaching has occurred is an important consideration for in-situ oil shale extraction methods currently being developed. Lake Uinta formed when two much smaller freshwater lakes, one in the Uinta Basin and the other in the Piceance Basin, expanded and coalesced across the Douglas Creek arch. Early Lake Uinta inherited much of the topography in the freshwater lake and surrounding alluvial plains that preceded it, and the deep central lake area of Lake Uinta developed largely over the offshore area of the freshwater lake. A prolonged period of infilling followed the formation of Lake Uinta, creating broad lake-margin shelves prior to the onset of saline mineral deposition. These shelves almost certainly played a critical role in the evolution of the brine layer that accumulated in the deep central lake area. Broad marginal shelves formed as well around the Uinta Basin part of Lake Uinta. Brines that formed on those shelves also probably migrated to the deep central lake area in the Piceance Basin, as no saline minerals were deposited in the Uinta Basin until late in the history of Lake Uinta. Oil shale in the deep central lake consists of interbedded laminate oil shale beds that originated within the deep lake area, and blebby and streaked oil shale beds that were transported into the deep lake area by sediment gravity flows. Blebby and streaked oil shale beds contain carbonate clasts and siliciclastic clasts similar to lithologies found on the marginal shelves. It is possible that these clasts and the highly saline brines that evolved on the marginal shelves were incorporated into the same gravity flows. Saline mineral deposition is informally subdivided into early, middle, and late phases. During the early phase, nahcolite and rich oil shale were deposited in the deep central lake area, and carbonate-rich sandstone, siltstone, and mudstone and ostracodal, oolitic, algal limestone were deposited on the marginal shelves. During the middle saline mineral phase, oil shale deposition gradually expanded across the marginal shelves, and by the end of that phase, oil shale deposition covered almost all of the former shelf areas. An increasing flow of water from Lake Gosiute to the north, as it was gradually filled in by volcaniclastics, may have caused this expansion. Saline mineral deposition also expanded during the middle saline mineral phase, reaching to near the former shelf break by the end of that phase. This suggests that the former shelf break remained a topographic feature that confined the deep saline brine layer throughout the middle phase. By the beginning of the late saline mineral phase, Lake Gosiute had been completely filled in and volcaniclastic debris reached the northern shore of Lake Uinta. This initiated a north-to-south infilling of the Piceance Basin part of Lake Uinta that progressively pushed the saline mineral area southward and ultimately onto the former marginal shelf areas in the southern part of the basin. A saline mineral area formed for the first time in the eastern part of the Uinta Basin during this infilling and, for a time, saline minerals were deposited in both basins. By the end of the late saline phase, the Piceance Basin part of Lake Uinta was filled in and saline mineral deposition shifted entirely into the Uinta Basin. Leaching of saline minerals began sometime after the Green River Formation was lithified enough to allow collapse breccias to form. Leaching is ongoing today, indicated by the discharge of highly saline water from a series of springs in the northern part of the basin. Groundwater invasion and saline mineral dissolution is commonly incomplete in areas that lack fractures, leaving behind pockets of unleached saline minerals in otherwise leached intervals. Today, the base of the leached zone slopes toward the north and toward the area where the brines are being discharged.

Colorado, Utah, Wyoming↗

USGS2025

Timing of hydrothermal alteration and Au-Sb-W mineralization, Stibnite-Yellow Pine district, Idaho

The Stibnite-Yellow Pine district of central Idaho was mined from the early 1900s until the 1990s, extracting gold, antimony, tungsten, and mercury from veins and disseminated and replacement ores in mountainous terrain along the headwaters of the Salmon River. Mining during the two World Wars supplied critical antimony and tungsten to the war efforts. Recent exploration has delineated mineral resources of over 187 metric tons Au, 274 metric tons Ag, and 93,000 metric tons Sb. Mineralization is hosted in Cretaceous Idaho batholith granitic rocks and a sequence of Neoproterozoic to Paleozoic metasedimentary strata of carbonate and siliciclastic compositions. Historical studies outlined some of the complex paragenesis but debated the absolute age of mineralization. New petrographic and geochronologic work documents a sequence of five hydrothermal events in the Stibnite-Yellow Pine district. Event 1 is related to Cretaceous magmatic and hydrothermal activity and includes events ranging in age from 86 to 75 Ma, including sparse quartz-molybdenite veins dated at 86 Ma. Disseminated gold mineralization of event 2 is associated with sericitic alteration and sulfidation of igneous biotite and replacement of plagioclase by potassium feldspar, largely in granodiorite. Gold is present in zoned arsenian pyrite in both disseminated ores and in crosscutting carbonate-quartz veins containing pyrite and arsenopyrite. The large Yellow Pine deposit, localized at a dilatant bend in the Meadow Creek fault, hosts such disseminated and vein gold. Event 2 is interpreted as the major gold-forming event; 40 Ar/ 39 Ar ages of sericite and potassium feldspar alteration range, respectively, from 70 to 59 and 66 to 56 Ma. The long span is interpreted to reflect the age of gold mineralization and local overprinting by event 3. A narrower range from 66 to 61 Ma is interpreted to date the peak of gold mineralization and alteration. Event 3, tungsten mineralization with scheelite, is texturally later than event 2 gold and localized along the Meadow Creek structure. Event 3 scheelite has been dated by isotope dilution-thermal ionization mass spectrometry (ID-TIMS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb methods at 57 Ma. Event 4, best developed in the West End area, includes gold-silver–bearing quartz-carbonate-pyrite veins and breccias with epithermal textures and potassium feldspar alteration envelopes. Adularia from event 4 yields 40 Ar/ 39 Ar plateau ages of 52 to 51 Ma. Event 5 antimony and mercury mineralization consists of stibnite veins and breccia cements at the Yellow Pine and Hangar Flat deposits as well as cinnabar veins and replacements at the peripheral Fern and Hermes deposits; it is constrained by an LA-ICP-MS U-Pb date on scheelite (ca. 47 Ma) intergrown with stibnite. Minor propylitic and argillic alteration is evident in 47 Ma igneous dikes, which do not contain economic mineralization. The Au-Sb-W ores in the Stibnite-Yellow Pine mining district formed over an extended time period from about 70 to 45 Ma in multiple pulses that were localized along the Meadow Creek fault zone. Each event corresponds to episodes of magmatism and/or hydrothermal activity in the region. Insignificant event 1 skarn and molybdenum mineralization is similar in age to the Thompson Creek porphyry molybdenum deposit in central Idaho. Event 2 gold mineralization occurred during a magmatic gap in central Idaho but was synchronous with magmatism in the Bitterroot lobe further north; event 2 is similar in age to orogenic gold-arsenic mineralization at the Beartrack mine in eastern Idaho. Event 3 scheelite mineralization coincides with tungsten mineralization at the Quartz Creek deposit, late magmatism in the Bitterroot lobe, and rapid exhumation of the Atlanta lobe of the Idaho batholith. Event 4 gold mineralization is coincident with the onset of regional Challis magmatism and extension. Event 5 antimony and mercury mineralization is time-equivalent to epithermal gold mineralization in the nearby Thunder Mountain volcanic field and the peak of Challis magmatism.

Idaho↗

USGS1996

The composition of fluid inclusions in ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type Zn-Pb deposits Poland: Genetic and environmental implications

The composition of fluids extracted from ore and gangue sulfide minerals that span most of the paragenesis of the Silesian-Cracow district was determined using a newly developed ion chromatographic (IC) technique. Ionic species determined were Na+, NH+4, Ca2+, Mg2+, K+, Rb+, Sr2+, Ba2+, Cl-, Br-, F-, I-, PO3-4, CO2-3, HS-, S2O2-3, SO2-4, NO-3, and acetate. Mineral samples included six from the Pomorzany mine and one from the Trzebionka mine which are hosted in the Triassic Muschelkalk Formation, and two samples of drill core from mineralized Upper Devonian strata. Nine paragenetically identifiable sulfide minerals occur throughout the Silesian-Cracow district. These include from earliest to latest: early iron sulfides, granular sphalerite, early galena, light-banded sphalerite, galena, dark-banded sphalerite, iron sulfides, late dark-banded sphalerite with late galena, and late iron sulfides. Seven of the minerals were sampled for fluid inclusion analysis in this study. Only the early iron sulfides and the last galena stage were not sampled. Although the number of analyses are limited to nine samples and two replicates and there is uncertainty about the characteristics of the fluid inclusions analyzed, the data show clear temporal trends in the composition of the fluids that deposited these minerals. Fluid inclusions in minerals deposited later in the paragenesis have significantly more K+, Br-, NH+4, and acetate but less Sr2+ than those deposited earlier in the paragenesis. The later minerals are also characterized by isotopically lighter sulfur and significantly more Tl and As in the solid minerals. The change in ore-fluid chemistry is interpreted to reflect a major change in the hydrologic regime of the district. Apparently, the migrational paths of ore fluids from the Upper Silesian basin changed during ore deposition and the fluids which deposited early minerals reacted with aquifers with very different geochemical characteristics than those that deposited late minerals. The early fluids may have reacted primarily with Devonian and Lower Carboniferous carbonate aquifers deeper in the basin, whereas the later fluids appear to have had extensive contact with organic-rich rocks, probably the shallower Middle and Upper Carboniferous flysch associated with coal measures. High concentrations of toxic Tl and As occur in the readily oxidized marcasite and pyrite minerals deposited by the later fluids. In general, the geochemistry of both the early and late fluids may be explained by an evaporite related origin or by water-rock modification of a saline basinal brine. When compared to the composition of fluid inclusions in Mississippi Valley-type (MVT) ore minerals from the Ozark region of the United States, fluid inclusions in minerals from Silesian-Cracow are fundamentally different, containing more Ca2+, Mg2+, NH+4, Br-, Sr2+ and acetate in all mineral stages with significantly more K+ in later stage minerals. The differences in ore fluid chemistry between the two regions are consistent with the lithologic differences of the respective basins thought to be the source of the mineralizing brines.

Prace - Panstwowego Instytutu Geologicznego↗

USGS2024

Minerals Yearbook, volume III, Area Reports — International — Africa and the Middle East

The U.S. Geological Survey (USGS) Minerals Yearbook discusses the performance of the worldwide minerals and materials industries and provides background information to assist in interpreting that performance. Content of the individual Minerals Yearbook volumes follows: Volume I, Metals and Minerals, contains chapters about virtually all metallic and industrial mineral commodities important to the U.S. economy. Chapters on survey methods, summary statistics for domestic nonfuel minerals, and trends in mining and quarrying in the metals and industrial mineral industries in the United States are also included. Volume II, Area Reports: Domestic, contains a chapter on the mineral industry of each of the 50 States and Puerto Rico and the Administered Islands. This volume also has chapters on survey methods and summary statistics of domestic nonfuel minerals. Volume III, Area Reports: International, is published as four separate reports. These regional reports contain the latest available minerals data on more than 180 foreign countries and discuss the importance of minerals to the economies of these nations and the United States. Each report begins with an overview of the region’s mineral industries during the year. It continues with individual country chapters that examine the mining, refining, processing, and use of minerals in each country of the region and how each country’s mineral industry relates to U.S. industry. Most chapters include production tables and industry structure tables, information about Government policies and programs that affect the country’s mineral industry, and an outlook section. The USGS continually strives to improve the value of its publications to users. Constructive comments and suggestions by readers of the Minerals Yearbook are welcome.

Minerals Yearbook↗

USGS2024

Minerals Yearbook, volume III, Area Reports — International — Asia and the Pacific

The U.S. Geological Survey (USGS) Minerals Yearbook discusses the performance of the worldwide minerals and materials industries and provides background information to assist in interpreting that performance. Content of the individual Minerals Yearbook volumes follows: Volume I, Metals and Minerals , contains chapters about virtually all metallic and industrial mineral commodities important to the U.S. economy. Chapters on survey methods, summary statistics for domestic nonfuel minerals, and trends in mining and quarrying in the metals and industrial mineral industries in the United States are also included. Volume II, Area Reports: Domestic , contains a chapter on the mineral industry of each of the 50 States and Puerto Rico and the Administered Islands. This volume also has chapters on survey methods and summary statistics of domestic nonfuel minerals. Volume III, Area Reports: International , is published as four separate reports. These regional reports contain the latest available minerals data on more than 180 foreign countries and discuss the importance of minerals to the economies of these nations and the United States. Each report begins with an overview of the region’s mineral industries during the year. It continues with individual country chapters that examine the mining, refining, processing, and use of minerals in each country of the region and how each country’s mineral industry relates to U.S. industry. Most chapters include production tables and industry structure tables, information about Government policies and programs that affect the country’s mineral industry, and an outlook section. The USGS continually strives to improve the value of its publications to users. Constructive comments and suggestions by readers of the Minerals Yearbook are welcomed.

Minerals Yearbook↗

USGS2024

Minerals Yearbook, volume III, Area Reports — International — Europe and central Eurasia

The U.S. Geological Survey (USGS) Minerals Yearbook discusses the performance of the worldwide minerals and materials industries and provides background information to assist in interpreting that performance. Content of the individual Minerals Yearbook volumes follows: Volume I, Metals and Minerals , contains chapters about virtually all metallic and industrial mineral commodities important to the U.S. economy. Chapters on survey methods, summary statistics for domestic nonfuel minerals, and trends in mining and quarrying in the metals and industrial mineral industries in the United States are also included. Volume II, Area Reports: Domestic , contains a chapter on the mineral industry of each of the 50 States and Puerto Rico and the Administered Islands. This volume also has chapters on survey methods and summary statistics of domestic nonfuel minerals. Volume III, Area Reports: International , is published as four separate reports. These regional reports contain the latest available minerals data on more than 180 foreign countries and discuss the importance of minerals to the economies of these nations and the United States. Each report begins with an overview of the region’s mineral industries during the year. It continues with individual country chapters that examine the mining, refining, processing, and use of minerals in each country of the region and how each country’s mineral industry relates to U.S. industry. Most chapters include production tables and industry structure tables, information about Government policies and programs that affect the country’s mineral industry, and an outlook section. The USGS continually strives to improve the value of its publications to users. Constructive comments and suggestions by readers of the Minerals Yearbook are welcomed.

Minerals Yearbook↗

USGS2024

Minerals Yearbook, volume III, Area Reports — International — Latin America and Canada

The U.S. Geological Survey (USGS) Minerals Yearbook discusses the performance of the worldwide minerals and materials industries and provides background information to assist in interpreting that performance. Content of the individual Minerals Yearbook volumes follows: Volume I, Metals and Minerals , contains chapters about virtually all metallic and industrial mineral commodities important to the U.S. economy. Chapters on survey methods, summary statistics for domestic nonfuel minerals, and trends in mining and quarrying in the metals and industrial mineral industries in the United States are also included. Volume II, Area Reports: Domestic , contains a chapter on the mineral industry of each of the 50 States and Puerto Rico and the Administered Islands. This volume also has chapters on survey methods and summary statistics of domestic nonfuel minerals. Volume III, Area Reports: International , is published as four separate reports. These regional reports contain the latest available minerals data on more than 180 foreign countries and discuss the importance of minerals to the economies of these nations and the United States. Each report begins with an overview of the region’s mineral industries during the year. It continues with individual country chapters that examine the mining, refining, processing, and use of minerals in each country of the region and how each country’s mineral industry relates to U.S. industry. Most chapters include production tables and industry structure tables, information about Government policies and programs that affect the country’s mineral industry, and an outlook section. The USGS continually strives to improve the value of its publications to users. Constructive comments and suggestions by readers of the Minerals Yearbook are welcomed.

Central America, South America↗

USGS2009

Mineral Commodity Summaries 2009

Each chapter of the 2009 edition of the U.S. Geological Survey (USGS) Mineral Commodity Summaries (MCS) includes information on events, trends, and issues for each mineral commodity as well as discussions and tabular presentations on domestic industry structure, Government programs, tariffs, 5-year salient statistics, and world production and resources. The MCS is the earliest comprehensive source of 2008 mineral production data for the world. More than 90 individual minerals and materials are covered by two-page synopses. For mineral commodities for which there is a Government stockpile, detailed information concerning the stockpile status is included in the two-page synopsis. Because specific information concerning committed inventory was no longer available from the Defense Logistics Agency, National Defense Stockpile Center, that information, which was included in earlier Mineral Commodity Summaries publications, has been deleted from Mineral Commodity Summaries 2009. National reserves and reserve base information for most mineral commodities found in this report, including those for the United States, are derived from a variety of sources. The ideal source of such information would be comprehensive evaluations that apply the same criteria to deposits in different geographic areas and report the results by country. In the absence of such evaluations, national reserves and reserve base estimates compiled by countries for selected mineral commodities are a primary source of national reserves and reserve base information. Lacking national assessment information by governments, sources such as academic articles, company reports, common business practice, presentations by company representatives, and trade journal articles, or a combination of these, serve as the basis for national reserves and reserve base information reported in the mineral commodity sections of this publication. A national estimate may be assembled from the following: historically reported reserves and reserve base information carried for years without alteration because no new information is available; historically reported reserves and reserve base reduced by the amount of historical production; and company reported reserves. International minerals availability studies conducted by the U.S. Bureau of Mines, before 1996, and estimates of identified resources by an international collaborative effort (the International Strategic Minerals Inventory) are the basis for some reserves and reserve base estimates. The USGS collects information about the quantity and quality of mineral resources but does not directly measure reserves, and companies or governments do not directly report reserves or reserve base to the USGS. Reassessment of reserves and reserve base is a continuing process, and the intensity of this process differs for mineral commodities, countries, and time period. Abbreviations and units of measure, and definitions of selected terms used in the report, are in Appendix A and Appendix B, respectively. A resource/reserve classification for minerals, based on USGS Circular 831 (published with the U.S. Bureau of Mines) is Appendix C, and a directory of USGS minerals information country specialists and their responsibilities is Appendix D. The USGS continually strives to improve the value of its publications to users. Constructive comments and suggestions by readers of the MCS 2009 are welcomed.

Mineral Commodity Summaries↗