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At least 865 records · Page 48Linked to original sources
USGS1913

Suggestions to authors of papers submitted for publication by the United States Geological Survey with directions to typewriter operators

The first pamphlet containing suggestions to authors for the preparation of manuscript intended for publication by the Geological Survey was published in January, 1888. This pamphlet was revised and reprinted in 1892. In 1904 the Survey published suggestions for the preparation of geologic folios, and in 1906 suggestions for the preparation of reports on mining districts. All matter of present value that was included in these publications, with much additional material, has been incorporated in the pamphlet here presented. The first edition of this pamphlet was published in 1909. The edition now published contains some new material and discusses in greater detail several suggestions that were made in the first edition. In the compilation of both editions valuable aid has been rendered by Mr. Bernard H. Lane, assistant editor.

Report↗
USGS1996

Chronology of Late Cretaceous igneous and hydrothermal events at the Golden Sunlight gold-silver breccia pipe, southwestern Montana

Gold mineralization at the Golden Sunlight breccia pipe, southwestern Montana, is related to emplacement of Late Cretaceous alkali-calcic rhyolite and subsequent collapse of the Belt Supergroup wallrock and rhyolite in the pipe. The pipe is inferred to grade downward into an alkalic porphyry molybdenum system. The pipe is cut by alkalic to sub-alkalic lamprophyre dikes and sills, which locally contain high-grade gold where emplaced along late shear zones and vein systems. Determination of the emplacement age of the rhyolite is hampered by inherited lead or inherited Late Archean zircon from the source region of the rhyolite. An emplacement age of about 80 Ma for the rhyolite can be inferred if a basement age of 2,600 Ma is assumed. This Late Archean age is in agreement with basement ages determined in many parts of southwestern Montana. A 206 Pb- 238 U whole-rock date of 84 ? 18 Ma from altered and mineralized Belt Supergroup strata and rhyolite in the breccia pipe indicates hydrothermal alteration related to gold mineralization in Late Cretaceous time. Although sericite is a relatively widespread hydrothermal mineral, attempts to date the very fine grained material by the 40 Ar- 39 Ar method did not provide a spectra that could be interpreted unambiguously. A 40 Ar- 39 Ar plateau date of 76.9 ? 0.5 Ma from biotite phenocrysts in the lamprophyre indciates intrusion of mafic magma and attendant CO 2 metasomatism in the Late Cretaceous. Fission-track data from zircon in the rhyolite are permissive of slow uplift of the Belt Supergroup strata, 1U.S. Geological Survey, Box 25046, Denver Federal Center, Denver, CO 80225. 2Golden Sunlight Mines, Inc., 453 MT Highway 2 East, Whitehall, MT 59759. rhyolite, and lamprophyre between 55 and 50 Ma, but the data are not definitive. Rhyolitic welded tuff in the informally named units 7, 9, and 11 of the Elkhorn Mountains Volcanics is most similar in chemistry and age to the rhyolite at the Golden Sunlight mine. Trachybasalt in the Adel Mountains Volcanics and andesitic basalt in the informally named unit 8 of the Elkhorn Mountains Volcanics are the most analogous in chemistry and age to lamprophyres at the mine. The rhyolitic rocks appear to be derived from deep crustal sources, but data for the lamprophyres and mafic rocks in the Elkhorn Mountains Volcanics indicate that they were derived from the mantle.

Bulletin↗
USGS2008

Radionuclide Data and Calculations and Loss-On-Ignition, X-Ray Fluorescence, and ICP-AES Data from Cores in Catchments of the Animas River, Colorado

The U.S. Departments of Agriculture and Interior Abandoned Mine Lands (AML) Initiative is focused on the evaluation of the effect of past mining practices on the water quality and the riparian and aquatic habitats of impacted stream reaches downstream from historical mining districts located primarily on Federal lands. This problem is manifest in the eleven western states (west of longitude 102 degrees) where the majority of hardrock mines that had past production are located on Federal lands. In areas of temperate climate and moderate to heavy precipitation, the effects of rapid chemical and physical weathering of sulfides exposed on mine-waste dumps and acidic drainage from mines have resulted in elevated metal concentrations in the stream water and stream-bed sediment. The result of these mineral weathering processes has an unquantified impact on the quality of the water and the aquatic and riparian habitats that may limit their recreational resource value. One of the confounding factors in these studies is the determination of the component of metals derived from hydrothermally altered but unmined portions of these drainage basins. Several watersheds have been studied to evaluate the effects of acid mine drainage and acid rock drainage on the near-surface environment. The Animas River watershed in southwestern Colorado contains a large number of past-producing metal mines that have affected the watershed. Beginning in October 1996, the U.S. Geological Survey (USGS) began a collaborative study of these effects under the USGS-AML Initiative. In this report, we present the radionuclide and geochemical analytical results of sediment coring during 1997-1999 from two cores from oxbow lakes 0.5 mi. upstream from the 32nd Street Bridge near Durango, Colo., and from three cores from beaver ponds within the Mineral Creek drainage basin near Silverton, Colo.

Data Series↗
USGS2012

Geospatial database for regional environmental assessment of central Colorado.

In conjunction with the future planning needs of the U.S. Department of Agriculture, Forest Service, the U.S. Geological Survey conducted a detailed environmental assessment of the effects of historical mining on Forest Service lands in central Colorado. Stream sediment, macroinvertebrate, and various filtered and unfiltered water quality samples were collected during low-flow over a four-year period from 2004–2007. This report summarizes the sampling strategy, data collection, and analyses performed on these samples. The data are presented in Geographic Information System, Microsoft Excel, and comma-delimited formats. Reports on data interpretation are being prepared separately.

Colorado↗
USGS1954

Geology and zinc-lead-barite deposits in the area east of Cuba City, Wisconsin

The current study of the Wisconsin-Illinois-Iowa zinc-lead district (fig. 1) was begun in 1942, with the major emphasis placed on detailed mapping of geologic structure and ore deposits. Preliminary reports for several areas in the mining district have been prepared, and the present study of the are east of Cuba City, Wis., is a continuation of that program.

Wisconsin↗
USGS2002

Mineralogical characterization of strata of the Meade Peak phosphatic shale member of the Permian Phosphoria Formation: Channel and individual rock samples of measured section J and their relationship to measured sections A and B, central part of Rasmussen Ridge, Caribou County, Idaho

The Permian Phosphoria Formation of southeastern Idaho hosts one of the largest phosphate deposits in the world. Despite the economic significance of this Formation, the fine-grained nature of the phosphorite has discouraged detailed mineralogical characterization and quantification studies. Recently, selenium and other potentially toxic trace elements in mine wastes have drawn increased attention to this formation, and motivated additional study. This study uses powder X-ray diffraction (XRD), with Rietveld quantification software, to quantify and characterize the mineralogy of composite channel samples and individual samples collected from the stratigraphic sections measured by the U.S. Geological Survey in the Meade Peak Member of the Permian Phosphoria Formation at the Enoch Valley mine on Rasmussen Ridge, approximately 15 miles northeast of Soda Springs, Idaho.

Idaho↗
USGS1953

Results of exploration at the Old Leyden coal mine, Jefferson County, Colorado

Six diamond core holes totaling 2, 201 feet were drilled by the. U, S. Bureau of Mines under contract to the U. S. Atomic Energy Commission at the Old Leyden coal mine, Jefferson County, Colo. The holes were spotted on the basis of geologic mapping by the U. S. Geological survey and were drilled to explore the lateral and downward extent of a uranium-bearing coal and the associated carnotite deposits in the adjacent sandstone° The data obtained from the diamond-core holes helped to explain the geology and structural control of the deposit. The uranium is most abundant in a coal bed that in places has been brecciated by shearing. and then altered to a hard, dense, and silicified rock. The uraniferous coal is in the nearly vertical beds of the Laramie formation of Upper Cretaceous age. Small lenticular bodies of uraniferous material, 50 feet long, 25 to 30 feet wide, and 2 to 4 feet thick, occur at intervals in the coal and silicified coal over a strike length of about 800 feet. These bodies contain 0.10 to 0.50 percent uranium. Data obtained from the drilling indicate a discontinuous radioactive zone between these higher-grade bodies; assays of samples from the cores range from 0.001 to 0.10 percent uranium. All drill holes were probed by Survey and A. E. C. logging equipment and showed anomalies where the core assayed more than 0.005 percent uranium. Material of ore grade--0.10 percent uranium--was found in one core; the rock in the other five holes was of lower grade. The presence of the radioactive zone in all holes suggests, however, that uranium is distributed irregularly in a southerly plunging deposit which is exposed in the adit, on the outcrop, and in other diamond-drill holes that were put down by the lessee.

Colorado↗
USGS1954

The landslide of Sainte-Adresse cliff

The Sainte-Adresse Cliff in the neighborhood of Le Havre was subject in the past to repeated movements of greater of lesser scope which in 1944 have become markedly accentuated because of works on the "Atlantic Wall" and bomb and mine explosions. The situation became dangerous and required a complete study including geological and geotechnical surveys with borings and search of slip planes. The study enabled us to explain the mechanism of the observed movements and to establish a program of consolidating works.

Sainte-Adresse Cliff↗
USGS1978

Mercury analysis of sediments from cores in Clear Lake, Lake County, California

Cores of late Quaternary sediments were collected from several sites in Clear Lake (fig. 1). Samples from two of these cores (fig. 2, 3) have been analyzed for their mercury content as part of a study on the time of emplacement of the mercury ore body at the nearby Sulphur Bank mine (fig. 1). The samples were analyzed in laboratories of the U.S. Geological Survey by the mercury vapor detector method (Vaughn and McCarthy, 1964; Vaughn, 1967). The analyses of core 6, except samples 332, 341, 343, 386, 406, and 462, were done by Mr. Kam Leong (Table 1); the remaining analyses were done by Mr. Allen Meier. Analyses of core 10 (table 2) were done by Mr. Meier. Meier reported interference by organic material in the samples he analyzed. Because the two sets of data are not in agreement, most of the samples submitted to Leong and Meier are being reanalyzed.

California↗
USGS1971

Nonthermal springs of Utah

Data are presented for about 4,500 nonthermal springs that discharge in the State of Utah. Most major springs having discharge of several cubic feet per second or more are in or near mountain ranges or plateaus where precipitation is much greater than in other parts of the State. The largest instantaneous discharge observed at any spring was 314 cfs at Mammoth Spring in southwestern Utah. Discharges exceeding 200 cfs have been observed at Swan Creek Spring in extreme northern Utah, and discharges of 200 cfs have been reported for Big Brush Creek Spring in northeastern Utah. Maximum discharges generally are during or within a few weeks after the main period of snowmelt, which is usually from late April to the middle of June. The largest springs generally discharge form or very near carbonate rocks in which solution channels and fractures are numerous or from areas of porous or fractured volcanic rocks. Most nonthermal springs in Utah probably are variable springs – that is, their variability of discharge exceeds 100 percent. Most of the major springs discharge water that contains less than 500 ppm (parts per million) of dissolved solids, and most of the water is of the calcium bicarbonate type. Water from springs is used for domestic, municipal, irrigation, livestock, mining, and industrial purposes.

Utah↗
USGS2011

Hydrogeologic setting and simulation of groundwater flow near the Canterbury and Leadville Mine Drainage Tunnels, Leadville, Colorado

The Leadville mining district is historically one of the most heavily mined regions in the world producing large quantities of gold, silver, lead, zinc, copper, and manganese since the 1860s. A multidisciplinary investigation was conducted by the U.S. Geological Survey, in cooperation with the Colorado Department of Public Health and Environment, to characterize large-scale groundwater flow in a 13 square-kilometer region encompassing the Canterbury Tunnel and the Leadville Mine Drainage Tunnel near Leadville, Colorado. The primary objective of the investigation was to evaluate whether a substantial hydraulic connection is present between the Canterbury Tunnel and Leadville Mine Drainage Tunnel for current (2008) hydrologic conditions. Altitude in the Leadville area ranges from about 3,018 m (9,900 ft) along the Arkansas River valley to about 4,270 m (14,000 ft) along the Continental Divide east of Leadville, and the high altitude of the area results in a moderate subpolar climate. Winter precipitation as snow was about three times greater than summer precipitation as rain, and in general, both winter and summer precipitation were greatest at higher altitudes. Winter and summer precipitation have increased since 2002 coinciding with the observed water-level rise near the Leadville Mine Drainage Tunnel that began in 2003. The weather patterns and hydrology exhibit strong seasonality with an annual cycle of cold winters with large snowfall, followed by spring snowmelt, runoff, and recharge (high-flow) conditions, and then base-flow (low-flow) conditions in the fall prior to the next winter. Groundwater occurs in the Paleozoic and Precambrian fractured-rock aquifers and in a Quaternary alluvial aquifer along the East Fork Arkansas River, and groundwater levels also exhibit seasonal, although delayed, patterns in response to the annual hydrologic cycle. A three-dimensional digital representation of the extensively faulted bedrock was developed and a geophysical direct-current resistivity field survey was performed to evaluate the geologic structure of the study area. The results show that the Canterbury Tunnel is located in a downthrown structural block that is not in direct physical connection with the Leadville Mine Drainage Tunnel. The presence of this structural discontinuity implies there is no direct groundwater pathway between the tunnels along a laterally continuous bedrock unit. Water-quality results for pH and major-ion concentrations near the Canterbury Tunnel showed that acid mine drainage has not affected groundwater quality. Stable-isotope ratios of hydrogen and oxygen in water indicate that snowmelt is the primary source of groundwater recharge. On the basis of chlorofluorocarbon and tritium concentrations and mixing ratios for groundwater samples, young groundwater (groundwater recharged after 1953) was indicated at well locations upgradient from and in a fault block separate from the Canterbury Tunnel. Samples from sites downgradient from the Canterbury Tunnel were mixtures of young and old (pre-1953) groundwater and likely represent snowmelt recharge mixed with older regional groundwater that discharges from the bedrock units to the Arkansas River valley. Discharge from the Canterbury Tunnel contained the greatest percentage of old (pre-1953) groundwater with a mixture of about 25 percent young water and about 75 percent old water. A calibrated three-dimensional groundwater model representing high-flow conditions was used to evaluate large-scale flow characteristics of the groundwater and to assess whether a substantial hydraulic connection was present between the Canterbury Tunnel and Leadville Mine Drainage Tunnel. As simulated, the faults restrict local flow in many areas, but the fracture-damage zones adjacent to the faults allow groundwater to move along faults. Water-budget results indicate that groundwater flow across the lateral edges of the model controlled the majority of flow in and out of the aquifer (79 percent and 63 percent of the total water budget, respectively). The largest contributions to the water budget were groundwater entering from the upper reaches of the watershed and the hydrologic interaction of the groundwater with the East Fork Arkansas River. Potentiometric surface maps of the simulated model results were generated for depths of 50, 100, and 250 m. The surfaces revealed a positive trend in hydraulic head with land-surface altitude and evidence of increased control on fluid movement by the fault network structure at progressively greater depths in the aquifer. Results of advective particle-tracking simulations indicate that the sets of simulated flow paths for the Canterbury Tunnel and the Leadville Mine Drainage Tunnel were mutually exclusive of one another, which also suggested that no major hydraulic connection was present between the tunnels. Particle-tracking simulations also revealed that although the fault network generally restricted groundwater movement locally, hydrologic conditions were such that groundwater did cross the fault network at many locations. This cross-fault movement indicates that the fault network controls regional groundwater flow to some degree but is not a complete barrier to flow. The cumulative distributions of adjusted age results for the watershed indicate that approximately 30 percent of the flow pathways transmit groundwater that was younger than 68 years old (post-1941) and that about 70 percent of the flow pathways transmit old groundwater. The particle-tracking results are consistent with the apparent ages and mixing ratios developed from the chlorofluorocarbon and tritium results. The model simulations also indicate that approximately 50 percent of the groundwater flowing through the study area was less than 200 years old and about 50 percent of the groundwater flowing through the study area is old water stored in low-permeability geologic units and fault blocks. As a final examination of model response, the conductance parameters of the Canterbury Tunnel and Leadville Mine Drainage Tunnel were manually adjusted from the calibrated values to determine if altering the flow discharge in one tunnel affects the hydraulic behavior in the other tunnel. The examination showed no substantial hydraulic connection. The multidisciplinary investigation yielded an improved understanding of groundwater characteristics near the Canterbury Tunnel and the Leadville Mine Drainage Tunnel. Movement of groundwater between the Canterbury Tunnel and Leadville Mine Drainage Tunnel that was central to this investigation could not be evaluated with strong certainty owing to the structural complexity of the region, study simplifications, and the absence of observation data within the upper sections of the Canterbury Tunnel and between the Canterbury Tunnel and the Leadville Mine Drainage Tunnel. There was, however, collaborative agreement between all of the analyses performed during this investigation that a substantial hydraulic connection did not exist between the Canterbury Tunnel and the Leadville Mine Drainage Tunnel under natural flow conditions near the time of this investigation.

Colorado↗
USGS2023

Distribution of rare earth and other critical elements in lignites from the Eocene Jackson Group, Texas

Coal is increasingly evaluated as a source of rare earth elements (REEs) in the United States to address the overreliance on imported REEs. The objective of this study was to assess the distribution of REEs in lignites from selected mining areas in the Texas Gulf Coastal Plain region. Thirty-one archived lignite and rock samples previously collected by the U.S. Geological Survey were analyzed for their rare earth element and critical mineral content. These include samples from one core (5400 and 5500 lignite horizons) and two opencast lignite mines (Gibbons Creek 3500 and 4500 horizons, and San Miguel horizons A to D) in the Eocene Jackson Group of the Texas Gulf of Mexico Coastal Plain. Some lithologies in the Gibbons Creek 3500 and 4500 lignite-bearing sections have high total rare earth, yttrium (Y), and scandium (Sc) (REYSc) values, up to 7800 ppm (ash basis) REYSc. The lignite lithologies show an enrichment in rare earths, [samarium (Sm) through gadolinium (Gd)]. The basal Gibbons Creek 3500 lignite bench shows a heavy rare earth element enrichment pattern resembling that often seen in peats through high volatile A bituminous coals. The 5500 lignite sequence, overlying the latter lignite sections, shows a light rare earth enrichment. The San Miguel lignite benches have heavy rare earth enrichments with a negative europium (Eu) anomaly.

Texas↗
USGS2008

Quality of water and sediment in streams affected by historical mining, and quality of Mine Tailings, in the Rio Grande/Rio Bravo Basin, Big Bend Area of the United States and Mexico, August 2002

The U.S. Geological Survey, in cooperation with the International Boundary and Water Commission - U.S. and Mexican Sections, the National Park Service, the Texas Commission on Environmental Quality, the Secretaria de Medio Ambiente y Recursos Naturales in Mexico, the Area de Proteccion de Flora y Fauna Canon de Santa Elena in Mexico, and the Area de Proteccion de Flora y Fauna Maderas del Carmen in Mexico, collected samples of stream water, streambed sediment, and mine tailings during August 2002 for a study to determine whether trace elements from abandoned mines in the area in and around Big Bend National Park have affected the water and sediment quality in the Rio Grande/Rio Bravo Basin of the United States and Mexico. Samples were collected from eight sites on the main stem of the Rio Grande/Rio Bravo, four Rio Grande/Rio Bravo tributary sites downstream from abandoned mines or mine-tailing sites, and 11 mine-tailing sites. Mines in the area were operated to produce fluorite, germanium, iron, lead, mercury, silver, and zinc during the late 1800s through at least the late 1970s. Moderate (relatively neutral) pHs in stream-water samples collected at the 12 Rio Grande/Rio Bravo main-stem and tributary sites indicate that water is well mixed, diluted, and buffered with respect to the solubility of trace elements. The highest sulfate concentrations were in water samples from tributaries draining the Terlingua mining district. Only the sample from the Rough Run Draw site exceeded the Texas Surface Water Quality Standards general-use protection criterion for sulfate. All chloride and dissolved solids concentrations in water samples were less than the general-use protection criteria. Aluminum, copper, mercury, nickel, selenium, and zinc were detected in all water samples for which each element was analyzed. Cadmium, chromium, and lead were detected in samples less frequently, and silver was not detected in any of the samples. None of the sample concentrations of aluminum, cadmium, chromium, nickel, selenium, and zinc exceeded the Texas Surface Water Quality Standards criteria for aquatic life-use protection or human health. The only trace elements detected in the water samples at concentrations exceeding the Texas Surface Water Quality Standards criterion for human health (fish consumption use) was lead at one site and mercury at 10 of 12 sites. Relatively high mercury concentrations distributed throughout the area might indicate sources of mercury in addition to abandoned mining areas. Streambed-sediment samples were collected from 12 sites and analyzed for 44 major and trace elements. In general, the trace elements detected in streambed-sediment samples were low in concentration, interpreted as consistent with background concentrations. Concentrations at two sites, however, were elevated compared to Texas Commission on Environmental Quality criteria. Concentrations of antimony, arsenic, cadmium, lead, silver, and zinc in the sample from San Carlos Creek downstream from La Esperanza (San Carlos) Mine exceeded the Texas Commission on Environmental Quality screening levels for sediment. The sample from Rough Run Draw, downstream from the Study Butte Mine, also showed elevated concentrations of arsenic, cadmium, and lead, but these concentrations were much lower than those in the San Carlos Creek sample and did not exceed screening levels. Elevated concentrations of multiple trace elements in streambed-sediment samples from San Carlos Creek and Rough Run Draw indicate that San Carlos Creek, and probably Rough Run Draw, have been adversely affected by mining activities. Fourteen mine-tailing samples from 11 mines were analyzed for 25 major and trace elements. All trace elements except selenium and thallium were detected in one or more samples. The highest lead concentrations were detected in tailings samples from the Boquillas, Puerto Rico, La Esperanza (San Carlos), and Tres Marias Mines, as might be expected because the tailings ar

Scientific Investigations Report↗
USGS1965

Barite in the United States, exclusive of Alaska and Hawaii

The mineral barite, barium sulfate, is the chief source of barium and its compounds needed for many industrial processes and products. Barite is found the world over and is abundant and widely distributed throughout the United States. The barite deposits of the United States (exclusive of Alaska and Hawaii) are shown on the accompanying map. The principal geologic type of deposit is indicated by the shape of symbol and the relative importance of the deposit is indicated by the size of symbol. This text lists localities by State, and index numbers are keyed to the map. Localities are distinguished by name of mine, prospect, or geographic area; their coordinates are given to the nearest minute of latitude and longitude. Geologic relations of each occurrence, if known, are summarized briefly. The text and map were compiled from published and unpublished information, and at least one reference is given for each locality, if reports have been published. The listings in some States are preceded by a principal reference which is a major source of information about deposits in those States.

Mineral Investigations Resource Map↗
USGS1970

Influences of strip mining on the hydrologic environment of parts of Beaver Creek basin, Kentucky, 1955-66

This report is the third of a series on the environmental effects of strip mining of coal in Cane Branch basin, McCreary County, Ky. The series of reports, which is being published by the U.S. Geological Survey as Professional Paper 427, is the product of a cooperative study by several Federal and State agencies. The physical environment of the study areas and the history of mining in the basin are described in the first report, Professional Paper 427-A (Musser, 1963). Results obtained during the study period 1955-59 and definitions of terms are given in the second report, Professional Paper 427-B (Collier and others, 1964). The present report describes the results of the investigation since 1955, with emphasis on the period 1959-66.

Professional Paper↗
USGS2016

News from the seabed: Geological characteristics and resource potential of deep-sea mineral resources

Marine minerals such as manganese nodules, Co-rich ferromanganese crusts, and seafloor massive sulfides are commonly seen as possible future resources that could potentially add to the global raw materials supply. At present, a proper assessment of these resources is not possible due to a severe lack of information regarding their size, distribution, and composition. It is clear, however, that manganese nodules and Co-rich ferromanganese crusts are a vast resource and mining them could have a profound impact on global metal markets, whereas the global resource potential of seafloor massive sulfides appears to be small. These deep-sea mineral commodities are formed by very different geological processes resulting in deposits with distinctly different characteristics. The geological boundary conditions also determine the size of any future mining operations and the area that will be affected by mining. Similarly, the sizes of the most favorable areas that need to be explored for a global resource assessment are also dependent on the geological environment. Size reaches 38 million km 2 for manganese nodules, while those for Co-rich crusts (1.7 million km 2 ) and massive sulfides (3.2 million km 2 ) are much smaller. Moreover, different commodities are more abundant in some jurisdictions than in others. While only 19% of the favorable area for manganese nodules lies within the Exclusive Economic Zone of coastal states or is covered by proposals for the extension of the continental shelf, 42% of the favorable areas for massive sulfides and 54% for Co-rich crusts are located in EEZs

Marine Policy↗
USGS1952

Pitchblende deposits at the Wood and Calhoun mines, Central City mining district, Gilpin County, Colorado

Pitchblende has been mined in commercial quantities from four gold- and silver-bearing pyrite-sphalerite-galena veins that occur in an area about one-half mile square on the south side of Quartz Hill, Central City district, Gilpin County, Colo. These veins are the Kirk, the German-Belcher, the Wood, and the Calhoun. Two of these veins, the Wood and the Calhoun, were studied in an attempt to determine the geologic factors favorable for pitchblende deposition. All accessible workings at the Wood and East Calhoun mines were mapped by tape and compass, and the distribution of radioactivity was studied in the field. Channel and chip samples were taken for chemical assay to compare radioactivity with uranium content. The pitchblende-bearing veins cat both pre-Cambrian granite gneiss and quartz-biotite schist; however, the gneiss was the more favorable host rock. Two bostonite porphyry dikes of Tertiary(?) age were crosscut by the Wood and Calhoun veins. The pitchblende occurs in lenses erratically distributed along the veins and in stringers extending outward from the veins. In the lenses it forms hard'. masses, but elsewhere it is Soft and powdery. The pitchblende is contemporaneous with the pyrite bat earlier than the sphalerite and galena in the same vein. All the observed pitchblende was at depths of less than 400 ft. The veins probably cannot be mined profitably for the pitchblende alone under present conditions.

Circular↗
USGS1980

Resource estimation from historical data: Mercury, a test case

A simple technique based on historical records of tonnage and grade of ore produced provides a means for calculating how much of a mineral product will be available in the future at various average grades. Estimates made on this basis are independent of geologic considerations or changing economic and political factors, although they are based on mining history, which was largely determined by these factors. The relatively minor element, mercury, was used for the test case reported here, but the method has been found applicable to forecasts of resources for other mineral products. Mercury resources available in ore in which the average grade is as low as 0.1% are estimated to be 53 ??106kg (1.5 ??106flasks) for the United States and 1551 ??106kg (45 ??106flasks) for the world; this amount is more than adequate to meet predicted demand to the year 2000. The expectable price of mercury in 1978 dollars at this 0.1% grade is projected to be $58.75 per kg ($2,025 per flask), but at a 10% annual inflation rate, it would be more than $12,000 per flask. To satisfy just the projected U.S. demand for mercury by 2000, the price is calculated to be $48.96 per kg ($1,688 per flask) in 1978 dollars at an average annual grade of 0.12%. ?? 1980 Plenum Publishing Corporation.

Journal of the International Association for Mathe↗