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USGS1971

Fluid-inclusion evidence on the environment of formation of mineral deposits of the southern Appalachian valley

Approximately 1,330 fluid inclusions were studied in samples of ore and gangue minerals from both massive ore and late-stage vugs from a series of Appalachian deposits and five active mines in the East Tennessee zinc districts. Most primary inclusions in sphalerite, fluorite, dolomite, and quartz from East Tennessee homogenized at 82 degrees -149 degrees C. Most primary inclusions in fluorite, barite, and sphalerite from the Central Kentucky, Central Tennessee, and Sweetwater barite districts, ranged from 72 degrees -132 degrees C. Pressure corrections to be added are probably less than 10 degrees C.Freezing data were obtained as a crude measure of the salinity of the inclusion fluids. With few exceptions, all primary inclusions contained very strongly saline brines (mostly >20 weight percent salts), with appreciable amounts of at least some salts other than NaCl, and some contained immiscible globules of oil. The exceptions include several quartz, fluorite, calcite, and barite samples that contained only moderately saline brines (12-16 percent), and some inclusions containing essentially fresh water, in vug calcite. Secondary inclusions had lower salinities than adjacent primaries. Eight primary inclusions in the differently colored outer millimeter of one Central Kentucky fluorite had low salinity (4-6 percent).The data indicate that all these deposits formed from hot, saline brines, with sphalerite forming from slightly hotter and more saline fluids than later gangue minerals. This places severe restrictions on possible modes of origin and makes deeply circulating connate brines the most probable ore fluids. The data give no information on the cause or direction of fluid circulation, which would be controlled by topography, salinity, and temperature during ore deposition, and they permit wide latitude in the construction of possible models. Other observations, on "colloform" textures, seem to indicate the admixture of at least small amounts of surface waters with the brines.

Kentucky, Tennessee, Virginia↗

USGS1977

Preliminary report on certain metals of potential economic interest in thin vanadium-rich zones in the Meade Park member of the Phosphoria Formation in western Wyoming and eastern Idaho

Electron microprobe, optical and chemical studies of fresh and weathered rocks permit preliminary conclusions concerning the concentration and mineralogical residence of certain elements of potential economic significance in thin, vanadium-rich zones in the Meade Peak Member of the Phosphoria Formation in western Wyoming and eastern Idaho. Elements of particular interest are V, Cr, Zn, Cd, Ag, Se, S, Ti, and Mo. Their principal mineralogical residence in fresh or unweathered rock has been established as follows: V is in, or associated with, organic material and minor amounts of V are in Ti-Fe oxysulfide and an unidentified Fe sulfide; Cr is in a 10 A mica. Zn and Cd are in sphalerite; Se is in pyrite; S is in pyrite, sphalerite and organic material; Ti is in TiO 2 and Ti 2 Fe(SO 3 ) 2 and Mo is in powellite. The principal minerals in fresh rocks are quartz, K-feldspar, albite, illite, calcite, and dolomite. Weathering or leaching by ground water removes pyrite, calcite, and dolomite. The leached rock sequences currently mined for phosphate may be amenable to extraction of the metals associated with the organic material.

Idaho, Wyoming↗

USGS2014

Succession of Laramide magmatic and magmatic-hydrothermal events in the Patagonia Mountains, Santa Cruz County, Arizona

This investigation of the space-time progression of magmatism and hydrothermal activity in the Patagonia Mountains of southern Arizona is based on field and paragenetic relationships, and on U-Pb and 40 Ar/ 39 Ar geochronology of igneous and hydrothermal minerals. The Patagonia Mountains consist of Precambrian, Paleozoic, and Mesozoic sedimentary, granitic, and volcanic rocks, Laramide volcanic rocks, and a core of Laramide intrusions that comprise the Patagonia Mountains batholith. Laramide igneous rocks and adjacent Paleozoic and Mesozoic rocks contain significant porphyry Cu-Mo deposits, Mo-Cu breccia pipes, Ag replacement deposits, and numerous other Cu-Pb-Zn-Ag replacement and vein deposits. Ages of igneous and hydrothermal minerals from 20 U-Pb and 52 40 Ar/ 39 Ar determinations define four magmatic and magmatic-hydrothermal events that formed the batholith and altered parts of it and adjacent rocks; cumulatively the events span at least 16 m.y., from ~74 to 58 Ma. The oldest event of this succession includes the 74 Ma Washington Camp stock and spatially associated Cu-Pb-Zn-Ag replacement deposits in Paleozoic carbonate rocks of the Washington Camp-Duquesne district. Eruption of 73 to 68 Ma volcanic rocks in the northern part of the range was the next youngest event, which coincides temporally with replacement and vein deposits in Paleozoic carbonate rocks at the Flux mine (~71 Ma). An event at 65 to 62 Ma is marked by emplacement of small-volume quartz monzonite, granodiorite, and diorite intrusions, formation of the Ventura breccia deposit in Jurassic granite at 65 to 64 Ma, and formation of other Pb-Zn-Ag-Cu replacement and vein deposits (~62 Ma; Blue Nose and Morning Glory). The Red Mountain porphyry Cu-Mo system is hosted by ~62 Ma granodiorite and Laramide volcanic rocks (73–68 Ma) at the northern end of the batholith. It includes a deep, chalcopyrite-bornite resource (~60 Ma) that is associated with potassic and sericitic alteration and a near-surface chalcocite-enargite resource (60 Ma) that is associated with advanced, supergene-enriched argillic alteration. The youngest event includes the Sunnyside porphyry Cu-Mo system and a Cu-Mo breccia deposit at Red Hill (Four Metals mine), both of which formed in large-volume quartz monzonite, granodiorite, quartz monzonite porphyry, and quartz feldspar porphyry (~61–59 Ma). Similar to the Red Mountain system, the Sunnyside system consists of a deep chalcopyrite resource that occurs in ~60 to 59 Ma quartz feldspar porphyry, and a near-surface, slightly younger (~59–58 Ma) enargite-chalcocite-tennantite resource that occurs in quartz feldspar porphyry, quartz monzonite porphyry, and Mesozoic rocks. The Red Hill Cu-Mo breccia deposit is hosted by large-volume quartz monzonite, granodiorite, and quartz monzonite porphyry (~61–59 Ma). Discrepancies between field and paragenetic relationships and some analytic ages at Sunnyside and Red Hill preclude precise dating of mineralization stages, and may reflect disturbance of isotope systems by multiple, co-spatial to juxtaposed intrusive and hydrothermal events, and/or by unrecognized intrusions. Numerous vein and replacement deposits at the northern end of the batholith, including the Hardshell Ag resource and the Three R supergene chalcocite resource, are distal deposits of the Sunnyside and Red Mountain systems. Small, ~61 to 59 Ma Cu-Mo deposits in large-volume intrusions in the southern part of the batholith consist of hydrothermal quartz, biotite, K-feldspar, muscovite, chalcopyrite, and molybdenite. The age span of magmatic and magmatic-hydrothermal events in the Patagonia Mountains, minimally 16 m.y., is comparable to that of certain other magmatic-hydrothermal successions that contain porphyry Cu-Mo systems. Magmatic-hydrothermal events of the Wasatch-Oquirrh igneous trend, Utah, and the Boulder batholith, Montana, both span ~17 m.y. and include the Bingham and Butte porphyry Cu-Mo, vein and replacement deposits, respectively. Plutons and mineral deposits in the Pima district, Arizona, which includes the porphyry Cu-Mo deposits at Sierrita-Esperanza, Mission-Pima-San Xavier North, and Twin Buttes, formed over an interval of ~14 m.y. The diversity of igneous and hydrothermal products likely reflects evolutionary processes occurring at multiple sites in the lithosphere and at different time scales from >10 m.y. to less than the geochronologic precision currently achievable.

Arizona↗

USGS1977

Epithermal beryllium deposits in water-laid tuff, western Utah

Epithermal beryllium deposits in western Utah have distinctive geological and geochemical associations that provide guides to exploration for new resources of beryllium and associated metals. Beryllium deposits at Spor Mountain and the Honeycomb Hills are uniquely associated with topaz-bearing rhyolite of Late Tertiary age and are restricted to porous water-laid tuff and breccia that contains carbonate clasts. The beryllium deposits are near both local and regional faults that probably provided conduits for mineralizing fluids.The beryllium deposits contain sizable but uneconomic concentrations of fluorite, lithium (in smectite), manganese oxides, zinc (in smectite and manganese oxides), and uranium, as well as many trace elements. Distinctive zones of argillic and feldspathic alteration enclose the beryllium deposits and generally are parallel to the original stratification of the host tuff. Anomalous concentrations of fluorine, beryllium, cesium, lithium, gallium, niobium, and yttrium occur in relatively unmineralized tuff nearby; these elements form extensive but discontinuous halos around the Spor Mountain beryllium and fluorspar district.The mineralized areas at Spor Mountain and the Honeycomb Hills may be the tops of extensive altered zones that contain deep ore deposits. Anomalous molybdenum, lead, tin, and tungsten in beryllium deposits at Spor Mountain may indicate such leakage. Consideration of possible zonation of ore deposits suggests that if ore deposits do exist at depth, they are in greisens, banded tactites, and medium to high temperature veins similar to the tin-beryllium deposits in the York Mountains of Alaska.

Utah↗

USGS1953

Mineralogy and geochemistry of a uraniferous coal from the Red Desert Area, Sweetwater County, Wyoming

A sample of subbituminous uraniferous coal from the Red Desert, Sweetwater County, Wyo., was studied mineralogically. The coal contains gypsum (6 percent), kaolinite (1 percent), quartz (0.3 percent), calcite (trace), and limonite (trace). This suite of minerals and the absence of pyrite show that the coal has been subjected to weathering and oxidation. No uranium minerals have been found; mechanical fractionation has indicated that the uranium is associated with the organic constituents of the coal. The minerals that have been isolated contain 0.0006 percent uranium, a content which is to be expected for nonuraniferous sedimentary rocks. The organic components of the coal contain approximately 0.002 percent uranium. On the basis of material balance calculations, the organic components carry 98 percent of the uranium in the coal. Fischer assays of this weathered coal from the Red Desert indicate a yield of 16.7 gallons of tar per ton on low-temperature retorting. In view of the large reserve of subbituminous coal in the Red Desert, its probable ease of mining, and its tar yield, it may be desirable to carry out further evaluation of the coal as a fuel or raw material for the manufacture of tar or chemicals. If economic factors permit utilization of the coal, the uranium, although present in small percentages, could be recovered as a byproduct.

Wyoming↗

USGS1991

Geology of the Bayan Obo iron-rare-earth-niobium deposits, Inner Mongolia, China

The plate tectonic setting, regional geology, and certain aspects of the economic geology of the iron-rare-earth-niobium ore bodies at Bayan Obo, Inner Mongolia, China, were studied by a team of geologists from the Tianjin Geologic Research Academy and the U.S. Geological Survey between 1987 and 1989. These ore bodies were formed by hydrothermal replacement of Middle Proterozoic dolomite in an intracontinental rift setting. A variety of veins and/or dikes that have a carbonatite-like mineralogy cut the footwall clastic rocks and migmatites. The hanging wall is a shale that has been converted to a K-metasomatite and has microcrystalline potassium feldspar as its principal constituent. This shale served as a scaling caprock that contained the chemical solutions that reacted with the dolomite and created the enormous concentration of mineralized rock in an 18-kilometer-long syncline. The rocks that host these ore bodies and the associated mineralized areas occur today as roof pendants in granitoid rocks of Permian age.

Conference Paper↗

USGS1996

Iron and manganese oxide mineralization in the Pacific

Iron, manganese, and iron-manganese deposits occur in nearly all geomorphologic and tectonic environments in the ocean basins and form by one or more of four processes: (1) hydrogenetic precipitation from cold ambient seawater, (2) precipitation from hydrothermal fluids, (3) precipitation from sediment pore waters that have been modified from bottom water compositions by diagenetic reactions in the sediment column and (4) replacement of rocks and sediment. Iron and manganese deposits occur in five forms: nodules, crusts, cements, mounds and sediment-hosted stratabound layers. Seafloor oxides show a wide range of compositions from nearly pure iron to nearly pure manganese end members. Fe/Mn ratios vary from about 24 000 (up to 58% elemental Fe) for hydrothermal seamount ironstones to about 0.001 (up to 52% Mn) for hydrothermal stratabound manganese oxides from active volcanic arcs. Hydrogenetic Fe-Mn crusts that occur on most seamounts in the ocean basins have a mean Fe/Mn ratio of 0.7 for open-ocean seamount crusts and 1.2 for continental margin seamount crusts. Fe-Mn nodules of potential economic interest from the Clarion-Clipperton Zone have a mean Fe/Mn ratio of 0.3, whereas the mean ratio for nodules from elsewhere in the Pacific is about 0.7. Crusts are enriched in Co, Ni and Pt and nodules in Cu and Ni, and both have significant concentrations of Pb, Zn, Ba, Mo, V and other elements. In contrast, hydrothermal deposits commonly contain only minor trace metal contents, although there are many exceptions, for example, with Ni contents up to 0.66%, Cr to 1.2%, and Zn to 1.4%. Chondrite-normalized REE patterns generally show a positive Ce anomaly and abundant ΣREEs for hydrogenetic and mixed hydrogenetic-diagenetic deposits, whereas the Ce anomaly is negative for hydrothermal deposits and ΣREE contents are low. However, the Ce anomaly in crusts may vary from strongly positive in East Pacific crusts to slightly negative in West Pacific crusts, which may reflect the redox conditions of seawater. The concentration of elements in hydrogenetic Fe-Mn crusts depends on a wide variety of water column and crust surface characteristics, whereas concentration of elements in hydrothermal oxide deposits depends of the intensity of leaching, rock types leached, and precipitation of sulphides at depth in the hydrothermal system.

Geological Society Special Publication↗

USGS1960

The chief oxide-burgin area discoveries, East Tintic district, Utah; A case history

The Burgin shaft is in the Chief Oxide area of the E. Tintic district, Utah, and is about a mile E. of any previously known ore bodies; workings from it are currently developing a substantial amount of commercial Pb-Zn ore in several blind ore bodies that lie in folded Paleozoic carbonate rock concealed beneath a blanket of Eocene lava. This area was mapped by Tower and Smith of the U.S. Geological Survey in 1897 and again by Lindgren and Loughlin in 1911, but no detailed work was done until after 1943 when a field party headed by T.S. Lovering began a study of the entire E. Tintic district. The history of the development of exploration concepts is summarized under Historical Summary. The E. Tintic mining district is in the E.-central part of a N.-trending fault-block mountain range near the eastern margin of the Great Basin; dominant structures of the range are a N.-trending syncline on the W. and a less well exposed anticline on the E. Both folds are cut by an intersecting system of transcurrent strike-slip faults and by minor thrust faults and normal faults of moderate displacement. A strong W.-dipping thrust fault cuts the anticline a short distance E. of the fold axis, but is hidden by Eocene lava throughout the E. Tintic district. The pre-Tertiary rocks range from Lower Cambrian to Upper Mississippian and exceed 7,000 ft. in total thickness; they are dominantly marine limestone and dolomite except for a thick basal Cambrian quartzite. The Tertiary rocks are chiefly dacitic lavas and pyroclastic deposits that are intruded by moderately persistent dikes and irregular bodies of monzonite and quartz porphyry. Nearly all the faulting and folding took place before the extrusion of the lavas on a rugged Eocene erosion surface. At about the time of the intrusion of monzonitic magma, many of the faults in the Paleozoic rock were re-opened and in the overlying lava some fracturing took place which was later accented by hydrothermal alteration. Most of the ore mined in the E. Tintic district has come from Pb-Zn-Ag replacement bodies in shattered Jasperoidized hydrothermal dolomite at the intersection of low angle faults and steep mineralized NE.-trending cross fractures. The U.S. Geological Survey studies of 1943 to 1957 concentrated on detailed mapping of geology and alteration in the E. Tintic district, together with field and laboratory studies of the relation of alteration to stages of mineralization and ore deposition. Trenching and core drilling were carried on after World War II to aid in interpreting the subrhyolite geology, and the Chief Oxide area was 1 of 4 localities tested by drilling. Study of the fossils, lithology, and alteration shown here in a deep drill core, together with the knowledge of the regional geology, led to an essentially correct interpretation of subrhyolite structure in the strongly discordant underlying Paleozoic rocks in which a mineralized tear fault cuts a strong thrust fault, and to the conclusion that ore stage mineralization was present in substantial amounts in the Paleozoic rocks below the Chief Oxide alteration patch in the quartz latite lava. Subsequent geothermal and geochemical work strengthened this conclusion, and the recent development work of the Bear Creek Mining Company, which sank the Burgin shaft, has shown the presence of Pb-Zn-Ag ore of commercial grade in substantial amount in blind ore bodies below the lava blanket in the Chief Oxide area.

Utah↗

USGS1961

Sandstone-type uranium deposits at Ambrosia Lake, New Mexico-An interim report

The Ambrosia Lake district in northwestern New Mexico is the most important uranium mining and milling district in the United States. Together with the nearby Laguna district it contains more than 50 percent of the nation's reserves.Most of the ore occurs in the Morrison formation of Late Jurassic age as elongate, tabular, mantolike bodies principally in the upper half of the Westwater Canyon sandstone member and near the base of the Poison Canyon sandstone tongue (9). Individual deposits are distributed along two easterly trending belts 2 to 3 miles apart. The ore bodies are as much as 3,000 feet long, several hundred feet wide, and 100 feet thick. Depths to the ore range from 0 to 2,200 feet. Some ore is also mined from the Todilto limestone of Late Jurassic age and from the Dakota sandstone of Early (?) and Late Cretaceous age.Two types of unoxidized ore are recognized: prefault ore, which is considered to be primary, and postfault ore, which may be redistributed. The prefault ore shows no obvious relationship to tectonic structures but appears to be controlled by a variety of sedimentary structures. Postfault ore is controlled by a combination of sedimentary and tectonic structures. Disseminated carbonaceous matter, believed to be plant derived, appears to be the dominant control in the localization of the uranium .The ore mineralogy is comparatively simple, and coffinite is by far the most abundant ore mineral. Molybdenum, selenium, vanadium, and iron occur in anomalous quantities in the deposits in both oxidized and unoxidized minerals.U/eU ratios and radioisotope distribution indicate almost universal disequilibrium and fairly recent migration of radioisotopes in all deposits that have been sampled.Further studies on the organic carbonaceous matter, sandstone alteration, age determinations, and sulfur isotope composition are required to obtain a better understanding of the source, transportation, and deposition of uranium and other elements in the deposits .

New Mexico↗

USGS1990

Genesis of the tabular-type vanadium-uranium deposits of the Henry Basin, Utah

Tabular-type vanadium-uranium deposits occur in fluvial sandstones of the Salt Wash Member of the Morrison Formation of Late Jurassic age The mineralized intervals and the weakly mineralized lateral extensions are bounded both above and below by zones rich in dolomite cement. Carbon isotope values of dolomite cements indicate that at least two sources of carbon existed. One source appears to be the same as that which formed the bedded carbonates in the evaporites in the Tidwell Member of the Morrison Formation stratigraphically below the mineralized interval. The second carbon source is typical of terrestrially deposited carbonates generally associated with meteoric water-dominated environments. Oxygen isotope values of these dolomites show the same trend of isotopically light values above the mineralized interval and isotopically heavier values in and below that interval; they indicate that two isotopically distinct fluids were involved in the mineralizing process. Some aspects of the origin of gangue and ore phases are explainable on the basis of processes which occurred solely within the saline fluid, but key aspects of ore genesis involved the interaction of the saline and meteoric waters. It is postulated that the solution interface migrated vertically within the stratigraphic section. -from Authors

Utah↗

USGS2002

Mineralogical characterization of weathered and less weathered strata of the Meade Peak phosphatic shale member of the Permian Phosphoria Formation: Measured sections E and F, Rasmussen Ridge, and measured sections G and H, Sage Creek area of the Webster Range, Caribou County, Idaho

The Permian Phosphoria Formation of the western U.S. includes one of the largest phosphate deposits in the world. Despite the economic significance of this formation, its fine-grained nature has discouraged detailed mineralogical characterization and quantitative studies. Recently, selenium and other potentially hazardous trace elements in mine wastes have drawn increased attention to these rocks and motivated more extensive study. Part of this effort has focused on a more detailed geological and mineralogical characterization of the rocks. This study uses powder X-ray diffraction (XRD) with Rietveld quantification software to characterize the mineralogy of channel samples from stratigraphic sections measured by the U.S. Geological Survey in the Meade Peak Phosphatic Shale Member of the Permian Phosphoria Formation. Measured sections are at the Rasmussen Ridge mine and at the Smoky Canyon mine approximately 15 and 25 miles, respectively, northeast of Soda Springs, Idaho. The dominant minerals present in these samples are carbonate-fluorapatite, which is the most common phosphatic ore mineral in this and other marine phosphorites, quartz, muscovite, albite, orthoclase, the ammonium feldspar buddingtonite (NH4AlSi3O8), dolomite, and calcite. Because of their potential for hosting trace elements such as Se, the presence of minor pyrite and sphalerite is also noteworthy. Analysis of the carbonate content in the carbonate-fluorapatite by Rietveld refinement shows relatively low carbonate contents, generally between 2 ? 3% (wt.) CO3 2- in the apatite structure, compared to other marine phosphorites.

Idaho↗

USGS2014

Porphyry copper assessment of western Central Asia

The U.S. Geological Survey conducted an assessment of resources associated with porphyry copper deposits in the western Central Asia countries of Kyrgyzstan, Uzbekistan, Kazakhstan, and Tajikistan and the southern Urals of Kazakhstan and Russia as part of a global mineral resource assessment. The purpose of the study was to (1) delineate permissive areas (tracts) for undiscovered porphyry copper deposits; (2) compile a database of known porphyry copper deposits and significant prospects; (3) where data permit, estimate numbers of undiscovered deposits within those permissive tracts; and (4) provide probabilistic estimates the amounts of copper (Cu), molybdenum (Mo), gold (Au), and silver (Ag) that could be contained in those undiscovered deposits. Western Central Asia, a region diverse in its geologic complexity, is situated north of the Tarim and North China tectonic blocks and sandwiched between the East European and Siberian cratons. The Ural Mountains form the western margin of the region; the southern margin is formed by the high-standing ranges that make up the Tian Shan mountain range in the border regions of Kazakhstan, Kyrgyzstan, and western China, where the effects of collisional tectonics are well displayed. The tectonic collage that makes up the core of western Central Asia is perhaps the geologically least understood part of the region. There is broad agreement that the early Paleozoic is made up of tectonically juxtaposed blocks that vary from Precambrian-cored microcontinents to magmatic arc and related complexes to subduction-related accretionary complexes. The rudiments of an incipient, contiguous single Kazakhstan block were formed by the end of the Silurian. In the middle to late Paleozoic, the block was unconformably superposed by two large, nested magmatic-arc belts, one Devonian, the other Carboniferous. Both magmatic-arc complexes were folded into a horseshoe-shaped, southeast-opening orocline in response to the final collisions of the various surrounding cratonic blocks with the Kazakhstan block. Additional deformation in the upper Cenozoic derived from the collision of India and China significantly redistributed fragments of the various mosaicked blocks, particularly in the central and southern parts of the western Central Asian region. Porphyry copper deposits are associated with many of the magmatic-arc fragments and belts throughout the geologically complex region, and economically important deposits are found in arc sequences of all Paleozoic Periods. The economically most productive arcs are Carboniferous. The assessment includes a discussion of the tectonic and geologic setting of porphyry copper deposits in western Central Asia (chapter 1), an application of remote sensing data for hydrothermal alteration mapping as a tool for porphyry copper assessment in the region (chapter 2), and a probabilistic assessment of undiscovered porphyry copper resources in four areas that represent Ordovician and Late Paleozoic (Carboniferous-Permian) magmatic arcs (chapter 3). The principal litho-tectonic terrane concept used to delineate permissive tracts was that of a magmatic arc that formed in the subduction boundary zone above a subducting plate. Eight permissive tracts are delineated on the basis of mapped and inferred subsurface distributions of igneous rocks assigned to magmatic arcs of specified age ranges that define areas where the occurrence of porphyry copper deposits within 1 kilometer of the Earth’s surface is possible. These tracts range in area from about 8,000 to 200,000 square kilometers and host 18 known porphyry copper deposits that contain about 54 million metric tons of copper. Available data included geologic maps, the distribution of significant porphyry copper occurrences and potentially related deposit types, the distribution of hydrothermal alteration patterns that are consistent with porphyry copper mineralization, and information on possible subsurface extensions of permissive rocks. On the basis of analyses of these data, the assessment team estimated a mean of 25 undiscovered porphyry copper deposits for the study area. Estimates of numbers of undiscovered deposits were combined with grade and tonnage models in a Monte Carlo simulation to yield a mean estimate of 95 million metric tons of copper in undiscovered porphyry copper deposits; this represents about twice the amount of identified porphyry copper resources (54 million metric tons). Detailed descriptions of each permissive tract, including the rationales for delineation and assessment, are given in appendixes, along with a geographic information system (GIS) that includes permissive tract boundaries, point locations of known porphyry copper deposits and significant occurrences, and hydrothermal alteration data based on analysis of remote sensing data.

Ural Mountains↗

USGS2015

Recent trends in Cuba’s mining and petroleum industries

In response to recent diplomatic developments between Cuba and the United States, the National Minerals Information Center compiled available information on the mineral industries of Cuba. This fact sheet highlights a new map and table that identify mines, mineral processing facilities, and petroleum facilities as well as information on location, operational status, and ownership. It also addresses the current status of known mineral industry projects, historical developments, and trends of the Cuban economy with an emphasis on mineral industries, and the supply and demand for Cuba’s mineral resources. In 2013, Cuba was estimated to be among the world’s top ten producers of cobalt and nickel, which are the country’s leading exports. Cuba’s current crude oil and associated natural gas production from onshore and shallow water coastal reservoirs is approximately 50,000 barrels per day of liquids and about 20,000 barrels per day oil equivalent of natural gas. In 2013, the value of mining and quarrying activities accounted for 0.6 percent of Cuba’s gross domestic product (GDP), compared with 1.4 percent in 2000. The value of production from Cuba’s industrial manufacturing sector increased by 88 percent between 1993 and 2013, whereas the sector’s share in the GDP decreased by about 3 percent during the same time period reflecting economic growth in other sectors of the economy.

Fact Sheet↗

USGS1978

Comments on classification of uranium resources

National resource assessments are intended to give some insight into future possibilities for the recovery of a desired resource. The resource numbers themselves only useful when related to economically controlled factors, such as industry capability as reflected in rated of production, rates of discovery, and technology development. To that end, it is useful to divide the resource base into component parts to which appropriate econometrics can be applied. A system of resource reporting adhering to these principles has been agreed to by the two major resource agencies in Government, the U>S. Geological Survey and the U.S. Bureau of Mines (USGS Bulletin 1450-A). Conceptually, then, a plan for resource reporting has been devised, and all resource reporting by these two agencies follows the agreed-upon pattern. Though conceptual agreement has been reached, each commodity has its own peculiar data problems; hence an operational definition to fit the conceptual pattern must be evolved for each mineral. Coal is the only commodity to date for which an operational agreement has been reached (USGS Bulletin 1450-B), but the basic essentials of an operational classification within the guideline of Bulletin 1450-A have been reported for oil and gas in USGS circular 725. The basic classification system is now well established and received general endorsement by Resources for the Future in a study of mineral resource classification systems prepared for the the Electric Power Research Institute (Schanz, 1976), and with respect to coal by the International Energy Agency.

Open-File Report↗

USGS1984

Application of mineral-solution equilibria to geochemical exploration for sandstone-hosted uranium deposits in two basins in west central Utah

A geochemical survey utilizing mainly ground waters was conducted in the Milford and Beaver basins. Waters were collected mainly from wells and springs at 100 sites and analyzed for major and minor elements. A computer model (WATEQ3) was used to calculate the redox potential and the state of saturation of the waters with respect to uraninite, coffinite, and other mineral phases. Several areas in the basins were shown to have ground-water environments of reducing redox potentials which are favorable for precipitation of reduced uranium minerals. In addition, the ground waters in some of these areas were shown to be saturated or near saturation with respect to uraninite and coffinite. These areas do not necessarily coincide with areas containing the highest concentrations of uranium in ground water. The methods described in this study for hydrogeochemical exploration for sandstone-hosted uranium deposits may have wide application, particularly throughout those filled basins in the western United States where nearby sources for uranium exist.

Economic Geology↗

USGS2022

Global tellurium supply potential from electrolytic copper refining

The transition towards renewable energy requires increasing quantities of nonfuel mineral commodities, including tellurium used in certain photovoltaics. While demand for tellurium may increase markedly, the potential to increase tellurium supply is not well-understood. In this analysis, we estimate the quantity of tellurium contained in anode slimes generated by electrolytic copper refining by country between 1986 and 2018, including uncertainties. For 2018, the results indicate that 1930 (1500-2700, 95% confidence interval) metric tons of tellurium were contained in anode slimes globally. This is nearly quadruple the reported tellurium production for that year. China has the greatest potential to increase tellurium supplies. However, most of the tellurium potentially recoverable by Chinese refineries appears to come from copper mined elsewhere. Further research into the business decisions associated with tellurium recovery may help translate the physical availability of tellurium into economic availability. The methodology presented here can be applied to other byproduct elements.

Resources, Conservation & Recycling↗

USGS2024

From exploration to production: Understanding the development dynamics of lithium mining projects

Recently, there has been considerable recent controversy whether current and new lithium mines will be able to supply the rapidly growing needs of the electromobility transition. Mineral exploration projects are typically active for many years, and only some become operational mines. From exploration to production, the projects go through several stages of characterisation and evaluation. At each stage, decisions are made by companies and stakeholders to advance, continue or stop the project. This is a complex process, and even projects with very similar geological and technical characteristics may take very different trajectories, depending on external factors such as global market conditions and local regulatory environments. The present study investigates the dynamics of this process for lithium exploration projects. A global database of 397 lithium projects was compiled, covering their progression through major development stages between 2004 and 2022. Ordinal logistic regression was used for the statistical analysis of this data. Different explanatory variables were tested, including economic, geological, technical, and geographic factors, to identify the best predictors for project progress at each development stage. The results suggest an essential role for lithium carbonate prices, and a variable role for other factors at each stage. Critically, the already elapsed lead time and project economics, which are traditionally considered important for the prediction of the start-up of individual mines, do not appear to be relevant in all cases. The results provide important insights into the dynamics of lithium supply and may eventually allow more realistic forecasts to be made for future lithium market dynamics.

Resources Policy↗

USGS1969

Evaluation and control of corrosion and encrustation in tube wells of the Indus Plains, West Pakistan

Seepage from rivers and irrigation canals has contributed to waterlogging and soil salinization problems in much of the Indus Plains of West Pakistan. These problems are being overcome in part by tube-well dewatering and deep leaching of salinized soils. The ground waters described here are anaerobic and some are supersaturated with troublesome minerals such as calcium carbonate (calcite) and iron carbonate (siderite). These waters are moderately corrosive to steel. Some wells contain sulfate-reducing bacteria, which catalyze corrosion, and pH-electrode potential relationships favorable to the solution of iron also are rather common. Corrosion is concentrated in the relatively active (anodic) saw slots of water-well filter pipes (screens), where metal loss is least tolerable. Local changes in chemical properties of the water, because of corrosion, apparently cause deposition of calcium carbonate, iron carbonate, and other minerals which clog the filter pipes. In some places well capacities are seriously reduced in very short periods of time. There appears to be no practicable preventive treatment for corrosion and encrustation in these wells. Even chemical sterilization for bacterial control has yielded poor results. Periodic rehabilitation by down-hole blasting or by other effective mechanical or chemical cleaning methods will prolong well life. It may be possible to repair severely damaged well screens by inserting perforated sleeves of plastic or other inert material. The most promising approach to future, well-field development is to use filter pipes of epoxy-resin-bonded fiber glass, stainless steel, or other inert material which minimizes both corrosion and corrosion-catalyzed encrustation. Fiberglass plastic pipe appears to be the most economically practicable construction material at this time and already is being used with promising results.

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