Geology, geochemistry, and mineralogy of the Ridenour Mine breccia pipe, Arizona
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Tintic, Park City, and Bingham have always been the three great silver-lead producing districts of Utah. Of late years Bingham has also become one of the most prominent copper districts of the world, and Tintic has likewise entered the ranks of the great copper camps.
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The Wood-East Calhoun mine area is underlain by complexly folded Precambrian gneiss and pegmatite. The major fold in the area is an anticline that trends about N. 60° E. The Precambrian rocks are intruded by bostonite porphyry dikes of Tertiary age. All the rocks are cut by east- to northeast - trending faults that have been filled by precious metal-sulfide veins which have been worked chiefly for gold. The Wood vein occurs in an east-trending fault; the Calhoun vein occurs in a northeast-trending fault. Much of the uranium production of the Central City district has come from the Wood vein on Quartz Hill. The veins consist chiefly of quartz; pyrite is the chief metallic mineral and chalcopyrite is next in abundance. Sphalerite, galena, tetrahedrite-tennantite, and pitchblende are locally present. Deposition began with alteration-stage quartz and pyrite followed in order by pitchblend, light-yellow pyrite, massive quartz, yellow pyrite, shalerite, comb quartz, chalcopyrite, tetrahedrite-tennantite, galena, chalcopyrite, pyrite, and gray to light-brown fine-grained quartz. The veins of the Central City district are zoned, with quartz-pyrite veins near the center and galena-sphalerite veins on the periphery. The known pitchblende bodies are in the transition between these, but paragenetically, the pitchblende is earlier than all other metallic minerals. A trace element study of the ore indicates an association of zirconium and molybdenum with uranium, of bismuth, antimony, and arsenic with copper, and of cadmium with zinc. The pitchblende and other ore minerals are concentrated in ore shoots. The shoots are in open spaces controlled by the competency of the wall rocks, the presence of a prevailing direction of weakness in the rocks, and changes in strike and dip of the vein. The pitchblende is thought to be a local constituent of the quartz-pyrite ores and to owe its origin to residual solutions from the quartz bostonite magma.
The W. Wilson mine, near Clancey, Mont., explores a siliceous vein in quartz monzonite of the Boulder batholith. The vein is a composite structure that consists of several closely spaced veinlets of quartz and chalcedony separated by silicified quartz monzonite. The vein has been recurrently brecciated and silicified. Typically, the quartz monzonite has been hydrothermally altered in zones of decreasing intensity outward from the vein. Pitchblende was deposited in and along the vein during one stage of the silicification that is characterized by fine-grained disseminated pyrite in black chalcedony. Subsequently most of the pitchblende was oxidized and hydrated to form a series of brightly colored secondary uranium minerals that exhibit a zonal relationship. Most of the known uranium minerals are localized in two small elongate ore bodies.
Alaska, the largest State within the United States, and mainly located north of latitude 60°, is an important part of the Circum-Arctic region. Alaska is a richly endowed region with a long and complex geologic history. The mining history is short by world standards but nevertheless there are a number of world-class deposits in Alaska, of which Red Dog and Pebble are among the largest of their respective types in the world. Alaska is a collection of geologic terranes or regions having distinct histories, most of which were tectonically assembled in the period from 400 million years to 50 million years ago (late Paleozoic through early Tertiary). They now occur as numerous fault-bounded blocks in the northernmost part of the North American Cordillera on the western margin of the Laurentian craton. These terranes are comprised of rocks ranging in age from Paleoproterozoic to Recent.
Coal Geology The Crumpler quadrangle lies in the Appalachian Plateaus province, with the coal bearing Pocahontas and New River Formations of Pennsylvanian age having a gentle dip toward the northwest. Coal bed maps were prepared (figures 1-7) and resources were estimated (table 1) for seven of the many coal beds in the Crumpler quadrangle (Stricker, 1980, lists the names of the various coal beds in the quadrangle) following methods established by U.S. Bureau of Mines and U.S. Geological Survey, 1976. All of these coal beds crop out at the surface in the quadrangle, have a maximum thickness thickness of over-burden of less than 300 meters, and have been mined at the surface, or under-ground, or both. Resource estimates were not calculated for other coal beds in the Pocahontas and New River Formations, either because of insufficient data of because of the beds are too thin. Figure 8 is a generalized stratigraphic column of the coal-bearing sequence in the Crumpler quadrangle showing thickness and relative positions of the various coal beds. The Crumpler quadrangle originally contained about 498 million metric tons of coal. Approximately 326 million metric tons have been mined, or lost in mining, leaving remaining resources of 172 million metric tons. Analyses of the mined coal beds in the Crumpler and adjacent quadrangle show the coal is medium - to low volatile bituminous (most are low volatile bituminous), containing 14-27 percent volatile matter (with an arithmetic mean of 18 percent), 2.1-22.4 percent ash (with an arithmetic mean of 7 percent), and 0.5-1.8 percent total sulfur (with an arithmetic mean of 0.8 percent). Heating values range from 6,380 to 8,610 Kcal/kg on an as-received basis. Trace element and major and minor oxide composition, of both whole coal and laboratory ash, for 59 samples within or near the quadrangle were obtained from USCHEM (Geochemical Data File or National Coal Resources Data System), (Kozey and others, 1980.) Neither elements of environmental concern such as arsenic, lead, mercury, and selenium nor potentially valuable elements such as germanium, uranium and thorium were found in significant amounts in the coal.
From December 1975 to September 1977 the U.S. Geological Survey studied coal mine drainage in western Washington to 1) characterize the water quality of drainage from abandoned mines in the 11 coal-bearing areas of the State; 2) examine the water quality effects on a stream receiving drainage from an abandoned coal mine; 3) determine the baseline water-quality conditions at two prospective underground coal mine areas; and 4) recommend procedures for monitoring stream quality in the baseline areas in the event that mining occurs. This report presents physical, chemical, and biological data collected during the study period from Gallop Creek (Whatcom County), Loretta Creek (Skagit County), and Wilkeson Creek (Pierce County) and from 100 abandoned coal mines in western Washington, and from a borehole hydraulic-mining test site. Biological information included taxonomic identifications and counts of benthic invertebrates and periphytic algae. (USGS)
The Powderhorn Wilderness Study Area (51,000 acres or 20,640 hectares) and the contiguous Cannibal Plateau Roadless Area (29,500 acres or 11,959 hectares) are on the Gunnison County-Hinsdale County boundary, approximately 50mi (80 km) southwest of Gunnison and a few miles east of Lake City, Colo. Part of the area has been known as the Powderhorn Primitive Area. The mineral resource potential of the study area has been assessed by the U.S. Geological Survey and the U.S. Bureau of Mines; this assessment involved, besides the geologic study and economic appraisal (Sharp and others, 1983), a geophysical survey (this report) by the Geological Survey, and a geochemical survey (Sharp and Lane, 1983) by the Geological Survey and the Bureau of Mines.
The Federal Land Policy and Management Act (Public Law 94-579, October 21, 1976) requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct mineral surveys on certain areas to determine their mineral resource potential. Results must be made available to the public and be submitted to the President and the Congress. These maps presents the results of a mineral survey of the Sheep Hole-Cadiz Wilderness Study Area (CDCA-305), California Desert Conservation Area, San Bernardino County, California. The U.S. Bureau of Mines conducted a mineral survey of the Sheep Hole-Cadiz Wilderness Study Area, which encompasses approximately 200,000 acres including enclosed private lands, in south-central San Bernardino County, California. The U.S. Bureau of Mines studied the mineral resources of mines, prospects, and mineralized areas; geologic, geochemical, and geophysical investigations were conducted by the U.S. Geological Survey. The study area is located in the Mojave Desert 13 miles east of Amboy, California, 20 miles east of Twentynine Palms, California, and 90 miles east of San Bernardino, and encompasses parts of the Dale Lake, Bristol Lake, Cadiz Valley and Cadiz Lake 15-minute quadrangles. Its borders are defined by the Amboy Road and a gas pipeline service road on the northwest, the unimproved Cadiz Valley access road on the east, State Route 62 along the south, and the Iron Age mine road and an unimproved powerline service road on the west. Major access from the east and west is provided by State Route 62 and access from the north is provided by the Amboy Road. Companion reports to this one describe the mineral resource potential (March and others, 1982), the geology (Howard and John, 1984), and hydrothermal alteration studies (Raines, 1983).
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