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At least 541 records · Page 30Linked to original sources
USGS1994

Prospector II: Towards a knowledge base for mineral deposits

What began in the mid-seventies as a research effort in designing an expert system to aid geologists in exploring for hidden mineral deposits has in the late eighties become a full-sized knowledge-based system to aid geologists in conducting regional mineral resource assessments. Prospector II, the successor to Prospector, is interactive-graphics oriented, flexible in its representation of mineral deposit models, and suited to regional mineral resource assessment. In Prospector II, the geologist enters the findings for an area, selects the deposit models or examples of mineral deposits for consideration, and the program compares the findings with the models or the examples selected, noting the similarities, differences, and missing information. The models or the examples selected are ranked according to scores that are based on the comparisons with the findings. Findings can be reassessed and the process repeated if necessary. The results provide the geologist with a rationale for identifying those mineral deposit types that the geology of an area permits. In future, Prospector II can assist in the creation of new models used in regional mineral resource assessment and in striving toward an ultimate classification of mineral deposits. ?? 1994 International Association for Mathematical Geology.

Mathematical Geology↗
USGS2012

Development and application of a soil organic matter-based soil quality index in mineralized terrane of the Western US

Soil quality indices provide a means of distilling large amounts of data into a single metric that evaluates the soil’s ability to carry out key ecosystem functions. Primarily developed in agroecosytems, then forested ecosystems, an index using the relation between soil organic matter and other key soil properties in more semi-arid systems of the Western US impacted by different geologic mineralization was developed. Three different sites in two different mineralization types, acid sulfate and Cu/Mo porphyry in California and Nevada, were studied. Soil samples were collected from undisturbed soils in both mineralized and nearby unmineralized terrane as well as waste rock and tailings. Eight different microbial parameters (carbon substrate utilization, microbial biomass-C, mineralized-C, mineralized-N and enzyme activities of acid phosphatase, alkaline phosphatase, arylsulfatase, and fluorescein diacetate) along with a number of physicochemical parameters were measured. Multiple linear regression models between these parameters and both total organic carbon and total nitrogen were developed, using the ratio of predicted to measured values as the soil quality index. In most instances, pooling unmineralized and mineralized soil data within a given study site resulted in lower model correlations. Enzyme activity was a consistent explanatory variable in the models across the study sites. Though similar indicators were significant in models across different mineralization types, pooling data across sites inhibited model differentiation of undisturbed and disturbed sites. This procedure could be used to monitor recovery of disturbed systems in mineralized terrane and help link scientific and management disciplines.

Environmental Earth Sciences↗
USGS1978

Identification and significance of accessory minerals from a bituminous coal

A scanning electron microscope (SEM) has been used to study the in situ accessory minerals in polished blocks and pellets of petrographically analysed samples of the Waynesburg coal (hvb). Individual grains from the low-temperature ash (LTA) of the same coal were also studied. The visual resolution of the SEM permitted the detection of submicron mineral grains, which could then be analysed by the attached energy-dispersive system. Emphasis was placed on the highly reflective grains in the carbominerite bands. Among the most abundant accessory minerals observed were rutile, zircon, and rare-earth-bearing minerals. Small (1–5 μm) particles of what may be authigenic iron-rich chromite and a nickel silicate form rims on quartz grains. The SEM also permits the observation of grain morphology and mineral intergrowths. These data are useful in determining authigenicity and diagenic alteration. Substances in density splits of LTA include authigenic, detrital, extraterrestrial magnetite, tourmaline, and evaporite (?) minerals, and a fluorine-bearing amphibole. This analytical approach allows the determination of specific sites for many of the trace elements in coals. In the Waynesburg coal, most of the chromium is in the iron-chromium rims, the fluorine is in the amphibole, and the rare-earth elements are in rare-earth-bearing minerals. The ability to relate trace-element data to specific minerals will aid in predicting the behaviour of elements in coal during combustion, liquefaction, gasification, weathering, and leaching processes. This ability also permits insight into the degree of mobility of these elements in coal and provides clues to sedimentological and diagenetic conditions.

Pennsylvania↗
USGS2009

Delineation of Magnesium-rich Ultramafic Rocks Available for Mineral Carbon Sequestration in the United States

The 2005 Intergovernmental Panel on Climate Change report on Carbon Dioxide Capture and Storage suggested that a major gap in mineral carbon sequestration is locating the magnesium-silicate bedrock available to sequester CO2. It is generally known that silicate minerals with high concentrations of magnesium are suitable for mineral carbonation. However, no assessment has been made covering the entire United States detailing their geographical distribution and extent, or evaluating their potential for use in mineral carbonation. Researchers at Columbia University and the U.S. Geological Survey have developed a digital geologic database of ultramafic rocks in the continental United States. Data were compiled from varied-scale geologic maps of magnesium-silicate ultramafic rocks. These rock types are potentially suitable as source material for mineral carbon-dioxide sequestration. The focus of the national-scale map is entirely on suitable ultramafic rock types, which typically consist primarily of olivine and serpentine minerals. By combining the map with digital datasets that show non-mineable lands (such as urban areas and National Parks), estimates on potential depth of a surface mine, and the predicted reactivities of the mineral deposits, one can begin to estimate the capacity for CO2 mineral sequestration within the United States. ?? 2009 Elsevier Ltd. All rights reserved.

Conference Paper↗
USGS2013

Quantifying mineral abundances of complex mixtures by coupling spectral deconvolution of SWIR spectra (2.1-2.4 μm) and regression tree analysis

This paper presents a methodology for assessing mineral abundances of mixtures having more than two constituents using absorption features in the 2.1-2.4 μm wavelength region. In the first step, the absorption behaviour of mineral mixtures is parameterised by exponential Gaussian optimisation. Next, mineral abundances are predicted by regression tree analysis using these parameters as inputs. The approach is demonstrated on a range of prepared samples with known abundances of kaolinite, dioctahedral mica, smectite, calcite and quartz and on a set of field samples from Morocco. The latter contained varying quantities of other minerals, some of which did not have diagnostic absorption features in the 2.1-2.4 μm region. Cross validation showed that the prepared samples of kaolinite, dioctahedral mica, smectite and calcite were predicted with a root mean square error (RMSE) less than 9 wt.%. For the field samples, the RMSE was less than 8 wt.% for calcite, dioctahedral mica and kaolinite abundances. Smectite could not be well predicted, which was attributed to spectral variation of the cations within the dioctahedral layered smectites. Substitution of part of the quartz by chlorite at the prediction phase hardly affected the accuracy of the predicted mineral content; this suggests that the method is robust in handling the omission of minerals during the training phase. The degree of expression of absorption components was different between the field sample and the laboratory mixtures. This demonstrates that the method should be calibrated and trained on local samples. Our method allows the simultaneous quantification of more than two minerals within a complex mixture and thereby enhances the perspectives of spectral analysis for mineral abundances.

Geoderma↗
USGS2012

Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life

The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.

Astrobiology↗
USGS2011

Microbial mineralization of dichloroethene and vinyl chloride under hypoxic conditions

Mineralization of 14C-radiolabled vinyl chloride ([1,2-14C] VC) and cis-dichloroethene ([1,2-14C] cis-DCE) under hypoxic (initial dissolved oxygen (DO) concentrations about 0.1 mg/L) and nominally anoxic (DO minimum detection limit = 0.01 mg/L) was examined in chloroethene-exposed sediments from two groundwater and two surface water sites. The results show significant VC and dichloroethene (DCE) mineralization under hypoxic conditions. All the sample treatments exhibited pseudo-first-order kinetics for DCE and VC mineralization over an extended range of substrate concentrations. First-order rates for VC mineralization were approximately 1 to 2 orders of magnitude higher in hypoxic groundwater sediment treatments and at least three times higher in hypoxic surface water sediment treatments than in the respective anoxic treatments. For VC, oxygen-linked processes accounted for 65 to 85% of mineralization at DO concentrations below 0.1 mg/L, and 14CO2 was the only degradation product observed in VC treatments under hypoxic conditions. Because the lower detection limit for DO concentrations measured in the field is typically 0.1 to 0.5 mg/L, these results indicate that oxygen-linked VC and DCE biodegradation can be significant under field conditions that appear anoxic. Furthermore, because rates of VC mineralization exceeded rates of DCE mineralization under hypoxic conditions, DCE accumulation without concomitant accumulation of VC may not be evidence of a DCE degradative “stall” in chloroethene plumes. Significantly, mineralization of VC above the level that could reasonably be attributed to residual DO contamination was also observed in several nominally anoxic (DO minimum detection limit = 0.01 mg/L) microcosm treatments.

Georgia↗
USGS2021

Mapping critical minerals from the sky

Critical mineral resources titanium, zirconium, and rare earth elements occur in placer deposits over vast parts of the U.S. Atlantic Coastal Plain. Key questions regarding provenance, pathways of minerals to deposit sites, and relations to geologic features remain unexplained. As part of a national effort to collect data over regions prospective for critical minerals, the first public high-resolution aeroradiometric survey over the U.S. Atlantic Coastal Plain was conducted over Quaternary sediments in South Carolina. The new data provide an unprecedented view of potential deposits by imaging Th-bearing minerals in the heavy mineral assemblage. Sand ridges show the highest radiometric Th values with localized, linear anomalies, especially along the shoreface and in areas reworked by multiple processes and/or during multiple episodes. Estuarine areas with finer-grained sediments show lower, distributed Th anomalies. Th values averaged over geologic unit areas are similar for both environments, suggesting that heavy minerals are present but have not been locally concentrated in the lower-energy estuarine environments. Radiometric K highlights immature minerals such as mica and potassium feldspar. K is elevated within shallow sediments younger than ca. 130 ka, an attribute that persists in regional data from northern South Carolina to northern Florida. Both K and Th are elevated over the floodplains of the Santee River and other rivers with headwaters in the igneous and metamorphic Piedmont Terrane. The persistence of K anomalies for distances of more than 100 km from the Santee River floodplain suggests that heavy minerals are delivered from the Piedmont to offshore areas by major rivers, transported along the coast by the longshore current, and redeposited onshore by marine processes.

Florida, Georgia, South Carolina↗
USGS1987

Near infrared detection of ammonium minerals

Diagnostic near-infrared spectral features have been identified for minerals with ammonium (NH (super +) 4 ) bound in the crystal structure. Spectral bands near 2.12, 2.02, and 1.56 mu m are characteristic of synthetic and natural NH 4 -bearing minerals. Laboratory spectra of NH 4 -bearing minerals are distinct from spectra of OH-bearing minerals and have diagnostic shifts in band position among different mineral types. NH 4 -bearing minerals were detected at several mineralized hot-spring deposits in the western U.S. by means of hand-held and airborne instruments. Near-infrared detection of NH 4 -bearing minerals may provide useful information for prospecting for certain ore deposits and may provide a better understanding of the nitrogen cycle within geologic environments.

Geophysics↗
USGS2013

Effect of organic matter properties, clay mineral type and thermal maturity on gas adsorption in organic-rich shale systems

A series of CH 4 adsorption experiments on natural organic-rich shales, isolated kerogen, clay-rich rocks, and artificially matured Woodford Shale samples were conducted under dry conditions. Our results indicate that physisorption is a dominant process for CH 4 sorption, both on organic-rich shales and clay minerals. The Brunauer–Emmett–Teller (BET) surface area of the investigated samples is linearly correlated with the CH 4 sorption capacity in both organic-rich shales and clay-rich rocks. The presence of organic matter is a primary control on gas adsorption in shale-gas systems, and the gas-sorption capacity is determined by total organic carbon (TOC) content, organic-matter type, and thermal maturity. A large number of nanopores, in the 2–50 nm size range, were created during organic-matter thermal decomposition, and they significantly contributed to the surface area. Consequently, methane-sorption capacity increases with increasing thermal maturity due to the presence of nanopores produced during organic-matter decomposition. Furthermore, CH 4 sorption on clay minerals is mainly controlled by the type of clay mineral present. In terms of relative CH 4 sorption capacity: montmorillonite ≫ illite – smectite mixed layer > kaolinite > chlorite > illite. The effect of rock properties (organic matter content, type, maturity, and clay minerals) on CH 4 adsorption can be quantified with the heat of adsorption and the standard entropy, which are determined from adsorption isotherms at different temperatures. For clay-mineral rich rocks, the heat of adsorption (q) ranges from 9.4 to 16.6 kJ/mol. These values are considerably smaller than those for CH 4 adsorption on kerogen (21.9–28 kJ/mol) and organic-rich shales (15.1–18.4 kJ/mol). The standard entropy (Δs°) ranges from -64.8 to -79.5 J/mol/K for clay minerals, -68.1 to -111.3 J/mol/K for kerogen, and -76.0 to -84.6 J/mol/K for organic-rich shales. The affinity of CH 4 molecules for sorption on organic matter is stronger than for most common clay minerals. Thus, it is expected that CH 4 molecules may preferentially occupy surface sites on organic matter. However, active sites on clay mineral surfaces are easily blocked by water. As a consequence, organic-rich shales possess a larger CH 4 -sorption capacity than clay-rich rocks lacking organic matter. The thermodynamic parameters obtained in this study can be incorporated into model predictions of the maximum Langmuir pressure and CH 4 - sorption capacity of shales under reservoir temperature and pressure conditions.

Conference Paper↗
USGS1982

Strata-bound sulfide deposits, wall-rock alteration, and associated tin-bearing minerals in the Carolina slate belt, South Carolina and Georgia

Massive sulfide deposits, gold deposits, and tin-bearing minerals occur in rocks of the Carolina slate belt in South Carolina and adjacent Georgia. The belt of greenschist metamorphic rocks in which the ore deposits occur is mostly Cambrian in age. It is divided into an upper metasedimentary unit and a lower unit of predominantly felsic metavolcanic and metavolcaniclastic rocks. The ore deposits occur in the lower unit chiefly near the contact between the two units. The rocks have been deformed into two maior sets of coaxial folds and at least two minor deformations. Coarse-grained unmetamorphosed Carboniferous, I-type granites, and abundant Triassic-Jurassic diabase dikes cut the slate belt and appear largely unrelated to the ore deposits. Remnants of Cretaceous and younger sedimentary rocks overlie the crystalline rocks near several of the larger mineralized areas.Massive sulfides, largely pyrite, and some polymetallic sulfides occur in mines opened for gold in the nineteenth century. The largest of these in South Carolina are the Haile, Brewer, and Dorn mines. These mines and the Little Mountain and Cedar Creek-Blythewood areas have many similar lithologic characteristics. These are: hydrothermally altered wall-rock consisting of quartz-sericite-kaolinite schist and quartz-sericite schist; abundant aluminous silicates such as kyanite, andalusite, pyrophyllite, and topaz; zones of iron-enriched rocks; and a suite of resistant heavy minerals that includes tin-bearing minerals. Heavy mineral concentrates from alluvium of small streams showed 20,000 ppm tin. Cassiterite and nigerite have been identified.At the Brewer mine, gold has been produced from altered felsic volcanic rocks that contain silicified breccia, massive topaz, abundant pyrite, minor enargite, and probably cassiterite. Massive pyrite and gold have been mined at the Haile mine. In the McCormick-Lincolnton area, a near-surface granitoid pluton is thought to be the source for volcaniclastic rocks that contain polymetallic massive sulfide deposits, gold, and associated deposits of kyanite, barite, and manganese. Tin was found there in heavy mineral concentrates, and rutile occurring with kyanite contains 1,000 ppm tin. At Little Mountain, cassiterite and hematite are present in rocks considered to be metamorphosed hot spring deposits. In the Cedar Creek-Blythewood area, nigerite is present, together with cassiterite, chrysoberyl, and seventeen other heavy minerals in concentrates panned from alluvium in streams draining an area of quartz-sericite-kaolinite schist.The deposition of massive sulfides, gold, and tin minerals is considered to be part of a continuum of volcanic activity that included alteration, deformation, and metamorphism. Altered rocks, which host the ore deposits, result from superimposed processes beginning with alteration syngenetic with the massive sulfides and ending with fracture-controlled alteration.

South Carolina↗
USGS2019

Discrete Zr and REE mineralization of the Baerzhe rare-metal deposit, China

Although REE (lanthanides + Y) mineralization in alkaline silicate systems is commonly accompanied with Zr mineralization worldwide, our understanding of the relationship between Zr and REE mineralization is still incomplete (e.g. Škoda and Novák, 2007; Linnen et al., 2014; Petrella et al., 2014; Möller and Williams-Jones, 2016; Wu et al., 2018). The Baerzhe deposit in NE China is a source of Zr, REE, and Nb linked to the formation of an early Cretaceous, silica-saturated, alkaline intrusive complex. In-situ laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of zircon and monazite crystals constrain the relationship between Zr and REE mineralization at Baerzhe. Three populations of zircon are identified and are differentiated based upon textural observations and compositional characteristics. Type I zircon display well-developed oscillatory zoning are are typically found as inclusions within sodic amphibole. Type II zircons are darker than Type I zircons in CL images, can overgrow Type I zircon, and have more irregular zoning and resorption features. Type III zircons contain irregular but translucent cores and rims with oscillatory zoning that are murky brown in color and grow in aggregates. Textural features and compositional data suggest that Types I and II zircon crystallized at the magmatic stage, with Type 1 being least altered and Type II being strongly altered, and Type III precipitated during the magmatic to magmatic-hydrothermal transition. Whereas the magnitude of the Eu anomaly is moderate in the barren alkaline granite, all three populations of zircon exhibit pronounced negative anomalies. Such features are difficult to explain exclusively by feldspar fractionation and could indicate the presence of fluid modification of the rocks. Monazite crystals occur mostly through replacement of zircon and sodic amphibole; monazite clusters are also present. Textural and compositional evidence suggests that monazite at Baerzhe is hydrothermal. Least and strongly altered magmatic zircon yield 207Pb-corrected 206Pb/238U ages of 127.3±1.2 Ma and 125.67±0.76 Ma, respectively. Deuteric zircon precipitated at 125.11±0.69 Ma. The chronological data suggest that the magmatic stage of the highly-evolved Baerzhe alkaline granite lasted less than two million years. Hydrothermal monazite records REE mineralization at 123.41±0.63 Ma, approximately 1 or 2 million years later than Zr mineralization. We therefore propose a model in which parental magmas underwent extensive magmatic differentiation while residual melts interacted with aqueous hydrothermal fluids. Deuteric zircon precipitated from a hydrosilicate liquid, and subsequent REE mineralization, exemplified by hydrothermal monazite, correlates with the metasomatic alteration from external fluid sources. Such interplay between magmatic and hydrothermal processes resulted in the formation of discrete Zr and REE mineralization at Baerzhe.

American Mineralogist↗
USGS2007

From Projectile Points to Microprocessors - The Influence of Some Industrial Minerals

In the language of economic geology, Earth materials are classified as metallic ores, fuel minerals, gemstones, and industrial minerals. Most people know that metallic ores yield shiny, conductive, ductile elements such as copper, iron, or gold. Most understand that energy-producing coals constitute a fuel mineral. Likewise, dazzling rubies and rare sapphires are universally recognized as gemstones. The fourth group, industrial minerals, is largely unknown to the general public, even though industrial minerals are as essential to daily life as metals and fuel minerals. This report examines the occurrence and practical uses of nine important industrial minerals - constituting just a few of the more than 50 industrial minerals that shape human culture.

Circular↗
USGS2016

Historical files from Federal Government mineral exploration-assistance programs, 1950 to 1974

The Defense Minerals Administration (DMA), Defense Minerals Exploration Administration (DMEA), and Office of Minerals Exploration (OME) mineral exploration programs were active over the period 1950–1974. Under these programs, the Federal Government contributed financial assistance in the exploration for certain strategic and critical minerals. The information about a mining property that was collected under these programs was placed in files called dockets. A docket is a collection of material (application, contract, correspondence, maps, reports, results) about a property for which an individual applied for exploration assistance from the Federal Government. Information found in dockets describe where mineral deposits were examined, what was found, and whether it was mined. As such, they provide very useful information to private industry regarding potential and non-potential prospect areas, provide the U.S. Geological Survey with useful information on mineral occurrences that are used in national assessments for particular mineral deposits, and provide other U.S. Federal agencies (Bureau of Indian Affairs, Bureau of Land Management, and Environmental Protection Agency) information relevant to land management, permitting, and leasing.

Data Series↗
USGS1992

Maps showing mineral resource assessment for copper and molybdenum in porphyry and stockwork deposits and for tungsten, iron, gold, copper, and silver in skarn deposits, Dillon 1° x 2° quadrangle, Idaho and Montana

This report is one of several in the series that assess the mineral resources of the Dillon quadrangle. For the purpose of the assessment, mineral deposits· in the quadrangle that are either known or suspected from a knowledge of the geologic setting have been grou~d into 30 deposit types on the basis of mineralogy, commodity, or structural or depositional setting. The emphasis in these assessment reports is on metallic minerals, but some important nonmetallic minerals will also be assessed. Fossil fuels are beyond the scope of this investigation; phosphate and uranium have been investigated previously (Swanson, 1970; Wodzicki andKrason, 1981); and certain nonmetallic. minerals, including bulk commodities such as sand and gravel, are in large supply and thus not considered. The ·mineral resource assessment discussed in this report considers two deposit types: (1) porphyry or stockwork deposits of copper. and molybdenum (referred to generally in this report as porphyry deposits) and (2) skarn deposits of tungsten, iron, gold, copper, and silver. Combining copper and molybenum porphyry deposits into a single deposit type is believed necessary for this purpose· mainly because the two metals are found together in most .deposits in the quadrangle, a geochemical signature unique to each has not been determined, and the significant petrologic characteristics of many associated plutons are not well known, especially characterist~cs of subsurface plutons whose presence is .inferred from geophysical data. In assessing mineral resources,· we have adopted a general philosophy similar to that of Harrison and others (19S6). We attempt to identify those parts of the quadrangle that are favorable for the occurrence of mineral resources. We do not attempt to locate specific exploration targets nor to determine the quantity of reserves or resources present.

Idaho, Montana↗
USGS1981

Map showing mineral resource potential of the Paiute Instant (Primitive) Study Area, Mohave County, Arizona

A geologic and geochemical investigation and a survey of the existing mines and prospects have been conducted to determine the mineral resource potential of the Paiute Instant (Primitive) Study Area, Mohave County, Ariz. The study area encompasses part of the Virgin Mountains and the Sullivans Canyon area. Precambrian metamorphic and igneous rocks are exposed in the core and are overlain by folded and faulted Paleozoic and Mesozoic quartzose and carbonate rocks. Mesozoic sedimentary rocks are overlain by Cenozoic volcanic and sedimentary units. The geochemical and mines and prospects survey indicates that the study area contains some mineral deposits that presently are not economically significant. Oil and gas has not been discovered in the area, and the resource potential is apparently nil or at best very low; any future oil and gas exploration would most likely be conducted outside the study area where favorable exploration localities exist. Other combustibles such as coal and oil shale are not known to occur in the study area. There is no evidence of geothermal activity or surficial radioactive mineralization. Several areas in the Paiute Instant Study Area are judged to have at best a low mineral potential. These include areas of copper, lead, manganese, molybdenum, nickel, silver, tungsten, and zinc mineralization, as well as occurrences of dumortierite, beryllium, arsenic, barium, gypsum, gem minerals, sand, gravel, and limestone. The metallic deposits and dumortieri te, beryllium, and arsenic occur over small surface areas. Significant production has not resulted from mining activity in mineralized areas. Sand, gravel, limestone, gem minerals, gypsum, and barium occurrences are far from major markets. Currently, there are no active mining operations in the study area.

Arizona↗
USGS1990

Map showing distribution of silver in the nonmagnetic fraction of heavy-mineral concentrates, Richfield 1° x 2° quadrangle, Utah

This map of the Richfield 1° x 2° quadrangle, Utah, shows the regional distribution of silver in the nonmagnetic fraction of heavy-mineral concentrates of drainage-sediment samples. It is part of a folio of maps of the Richfield 1° x 2° quadrangle, Utah, prepared under the Conterminuous United States Mineral Assessment Program. Other published geochemical maps in this folio are listed in the references (this publication). The Richfield quadrangle is located in west-central Utah and includes the eastern part of the Pioche-Marysvale igneous and mineral belt, which extends from the vicinity of Pioche in southeastern Nevada, east-northeastward for 155 miles into central Utah. The western two-thirds of the Richfield quadrangle is part of the Basin and Range province, whereas the eastern third is part of the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of Late Proterozoic and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks located in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrain into a series of north-trending fault blocks; the uplifted mountain areas were eroded to various degrees and the resulting debris was deposited in adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed as a result of igneous activity in the middle and late Cenozoic time. A more complete description of the geology and a mineral-resource appraisal of the Richfield quadrangle appears in Steven and Morris (1984 and 1987). The regional sampling program was designed to define broad geochemical patterns and trends that can be utilized along with geological and geophysical data to assess the mineral-resource potential for this quadrangle. Reconnaissance geochemical surveys are valuable tools in mineral exploration, especially when used in conjunction with data obtained from other earth science disciplines. Identifying specific exploration targets generally involves additional, more detailed investigations.

Utah↗
USGS2002

Mapped minerals at Questa, New Mexico, using airborne visible-infrared imaging spectrometer (AVIRIS) data – Preliminary report for: First quarterly report of the U.S. Geological Survey investigation of baseline and pre-mining ground-water quality in the Red River Valley Basin, New Mexico, November 13, 2001

This preliminary study for the First Quarterly Report has spectrally mapped hydrothermally altered minerals useful in assisting in assessment of water quality of the Red River. Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) data was analyzed to characterize mined and unmined ground at Questa, New Mexico. AVIRIS data covers the Red River drainage north of the river, from between the town of Questa on the west, to east of the town of Red River. The data was calibrated and analyzed using U.S. Geological Survey custom software and spectral mineral library. AVIRIS data was tested for spectral features that matched similar features in the spectral mineral library. Goodness-of-fit and band-depth were calculated for each comparison of spectral features and used to identify surface mineralogy. Mineral distribution, mineral associations, and AVIRIS pixel spectra were examined. Mineral maps show the distribution of iron hydroxides, iron sulfates, clays, micas, carbonates, and other minerals. Initial results show a system of alteration suites that overprint each other. Quartz-sericite-pyrite (QSP) alteration grading out to propylitic alteration (epidote and calcite) was identified at the Questa Mine (molybdenum porphyry) and a similar alteration pattern was mapped at the landslide ("scar") areas. Supergene weathering overprints the altered rock, as shown by jarosite, kaolinite, and gypsum. In the spectral analysis, hydrothermally altered ground appears to be more extensive at the unmined Goat Hill Gulch and the mined ground, than the ?scars? to the east. Though the "scars" have similar overall altered mineral suites, there are differences between the "scars" in sericite, kaolinite, jarosite, gypsum, and calcite abundance. Fieldwork has verified the results at the central unmined "scar" areas.

New Mexico↗