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Geology topics

Arthur S. Radtke

Publications and source records attributed to Arthur S. Radtke.

11 recordsLinked to original sources
USGS1985

Geology of the Carlin gold deposit, Nevada

This report describes the geology of the Carlin gold deposit and the Lynn mining district, including an area of about 80km 2 in northern Eureka County, Nev. (fig. 1). The Carlin mine is located in secs. 13 and 14, T.35N., R.50E., at an elevation of 6,400 ft near the crest of the Tuscarora Mountains. The map area (pl. 1), centered approximately on the Carlin mine, measures about 10km east-west by 8km north-south and forms approximately the south two-thirds of the Rodeo Creek NE. 7{1/2}-minute quadrangle. Boundaries for the map area are meridians 116°15'00" and 116°22'30" W. and parallels 40°52'30" and 40°57'30"N. The Carlin mine is accessible by an asphalt-surfaced road extending about 35km northward from the town of Carlin, Nev., which is on U.S. Highway 40. A secondary improved road extends from the Carlin mine westward into Boulder Valley and connects with both State Highway 18 to the north and U.S. Highway 40 to the south near the town of Dunphy. An unimproved road extends from the Carlin mine northward, along the west side of Little Boulder Basin, to the Blue Star mine, and continues northward and westward along Rodeo Creek to connect with a graded road extending northeastward along Boulder Valley. Numerous unimproved roads have been built to provide access to the different mining prospects.

Nevada↗
USGS1981

Geology of the Carlin gold deposit, Nevada

The Carlin gold deposit, near the crest of the Tuscarora Range in the Lynn mining district, about 35 km north of Carlin, Nev., is the largest hydrothermal disseminated-replacement deposit discovered to date in North America. The mine began production in 1965 and between 1965 and 1976 produced about 2 million troy ounces of gold.

Nevada↗
USGS1978

Occurrence and formation of avicennite, Tl2O3 , as a secondary mineral at the Carlin gold deposit, Nevada

Avicennite, Tl 2 O 3 , occurs as grains disseminated in silicified limestones in the upper part of the East ore zone of the Carlin gold deposit, Nevada. The avicennite is formed by the oxidation of carlinite, Tl 2 S, found in primary unoxidized carbonaceous ore immediately below the avicennite. The grains of avicennite closely resemble carlinite in size and shape. Some avicennite occurs as thin coatings on carlinite, but the time of its formation is unclear. Avicennite grains are polycrystalline, porous, dark gray to black, with a hackly fracture but no discernible cleavage. The Mohs hardness is 2.0±0.5; Vickers hardness ranges from 46.0 to 80.5 kg mm -2 . Measured density is distinctly low, 8.9 g cm -3 (or Mg m -3 ), relative to the calculated density, 10.34 g cm -3 . The mineral is isometric, space group Ia 3. a =10.5468±0.0003 angstroms or 1.05468±0.00003 nm, Z =16, and the volume of the unit cell is 1173.17±0.04 Ǻ 3 or 1.17317±0.00004 nm 3 . The most intense X-ray diffraction peaks are 3.044 (100), 1.864 (38), 2.637 (37), and 1.590 (30). In reflected light, avicennite is pale to medium gray and isotropic and lacks discernible bireflectance. Reflectance in air ranges from 10.6 to 13.0 percent. Avicennite is nearly pure Tl 2 O 3 , containing 89.6 weight percent Tl and 10.5 weight percent O by microprobe analysis. Other elements present, detected by emission spectrographic analysis, are: Pb, 300 ppm; Ca, 100 ppm; and Si, Al, Fe, Mg, Ag, Cr, Cu, Ni, and Ti, all <50 ppm.

Nevada↗
USGS1976

Statistical studies of selected trace elements with reference to geology and genesis of the Carlin gold deposit, Nevada

Linear regression and discriminant analyses techniques were applied to gold, mercury, arsenic, antimony, barium, copper, molybdenum, lead, zinc, boron, tellurium, selenium, and tungsten analyses from drill holes into unoxidized gold ore at the Carlin gold mine near Carlin, Nev. The statistical treatments employed were used to judge proposed hypotheses on the origin and geochemical paragenesis of this disseminated gold deposit.

Professional Paper↗
USGS1974

Thallium-bearing orpiment, Carlin gold deposit, Nevada

A variety of orpiment, As 2 S 3 , containing a significant amount of thallium has been identified in the unoxidized East ore body of the Carlin gold deposit. The mineral occurs in small veinlets with barite, calcite, quartz, and realgar.

Nevada↗
USGS1973

Antimony-bearing orpiment, Carlin gold deposit, Nevada

Orpiment, As 2 S 3 , containing up to 1.5 percent antimony has been recognized in carbonaceous arsenic-rich gold ores in the unoxidized East ore body of the Carlin gold deposit. Associated hydrothermal minerals include realgar (AsS) and quartz. Stibnite, commonly associated with realgar in the ores, has not been observed associated with this type of orpiment.

Nevada↗
USGS1973

New data on cuprobismutite

Cuprobismutite from Tunnel Extension Number Two mine, Ohio mining district, Utah, was chemically analyzed using the electron microprobe. Its empirical formula was determined to be Cu 20.8 Ag 0.97 Pb 0.35 Mn 0.22 Bi 26.7 Sb 0.06 Te 0.05 Se 0.55 S 50.4. The tentative conclusion is that unsubstituted cuprobismutite has the chemical formula 6Cu 2 S*6Bi 2 S 3 rather than the previously ascribed formula 6Cu 2 S*6Bi 2 S 3 and that cuprobismutite is therefore not dimorphous with emplectite.

Utah↗
USGS1970

Studies of hydrothermal gold deposition (I). Carlin gold deposit, Nevada: The role of carbonaceous materials in gold deposition

Studies of fresh carbonate host rocks and unoxidized gold ores of the Carlin mine indicate that gold, quartz, barite, pyrite, and other sulfides were introduced into the Roberts Mountains Formation by acid hydrothermal solutions. Laboratory investigations on the carbonaceous materials in the host rocks and ores and studies of reactions between carbonaceous materials and gold-bearing solutions show that the rocks contain: (1) An activated carbon component capable of adsorbing gold chloride or gold cyanide complexes from solution; (2) A mixture of high-molecular-weight hydrocarbons usually associated with the activated carbon components; and (3) An organic acid, similar to "humic acid," containing functional groups capable of interacting with gold complexes to form gold organic compounds. Although the exact structure of the gold organic compound(s) is not known, the most attractive possibility is chelation, where ligands such as N, S, or O in organic acids would easily displace the chloride ion from aurous chloride complexes and form stable gold chelates. Subsequent oxidation of the gold organic compounds destroys the organic component and leads to the formation of metallic gold. The relative amounts and types of carbonaceous materials are of principal importance in determining the chemical state and amount of gold deposited in carbonaceous limestone, although such factors as temperature, pH, and the oxidation state of the system are also involved.Although most of the gold ores at the Carlin mine are in the Silurian Roberts Mountains Formation and are at least several hundred feet stratigraphically below the Roberts Mountains thrust fault, disseminated replacement-type gold deposits could form in the lower-plate Devonian limestones (designated the Popovich Formation at the Carlin mine) and in carbonate and shale units of the upper-plate Ordovician Vinini Formation. In a structural setting that would provide satisfactory channels for movement of gold-bearing solutions, physical characteristics and chemical and mineralogical compositions, including the presence of organic materials, indicate that all three formations are favorable for replacement and deposition of gold.

Nevada↗
USGS1969

Micromineralogy of silver-bearing sphalerite from Flat River, Missouri

Detailed mineralogical and chemical study of sphalerite-rich lead ores from Flat River, Mo., confirms the presence of anomalous amounts of silver in the sphalerite. Although silver is closely associated with chlorine and no silver sulfide minerals were identified, geochemical considerations indicate the silver may be in the form of discrete submicron-size grains of sulfide rather than chloride. However, the close correlation between abundance variations in silver, chlorine, cadmium, iron, and minor lead suggests the possible existence of submicron-size grains of a complex chloride or oxychloride. Results from detailed chemical study of sphalerite show: (1) chlorine is present in areas containing silver and changes in abundance of both elements are similar; (2) the mole ratio of chlorine to silver varies from approximately 3:1 to 6:1 with an approximate average of 5:1 and the total content of each element varies widely between grains and within the same grain; (3) taking total silver in any analysis and calculating the amount of chlorine required for silver chloride leaves an excess of chlorine; (4) in chlorine-deficient areas the amounts of iron and cadmium substituting for zinc in the sphalerite structure vary widely; and (5) in areas containing chlorine, changes in abundance of iron and cadmium vary directly with that of chlorine. The fine-grained dusty opaque inclusions characterize sphalerite from this area; they were identified as mainly galena with lesser amounts of pyrite and cassiterite. Galena is silver-free (<0.02 weight percent Ag) and is essentially pure lead sulfide. Other sulfides identified include pyrite, a cobalt-nickel-iron sulfide of composition Co (sub 0.55) Ni (sub 0.25) Fe (sub 0.20) S (sub 2.00), and an iron-cobalt-nickel sulfide containing 22-28 weight percent Fe, 10-15 weight percent Co, and 3-5 weight percent Ni. Anomalous amounts of tin present as cassiterite are associated with the gangue minerals quartz, potash feldspar, a kaolinite-type clay, and trace amounts of cuprite. Carbonate gangue minerals include calcite, dolomite, ankerite, magnesite, and minor amounts of cerussite. Chemical analyses were made of many minerals and physical and textural relationships examined.

Missouri↗
USGS1967

Aurorite, argentian todorokite, and hydrous silver-bearing lead manganese oxide

During a study of hypogene manganese minerals, three silver-bearing manganese oxides were identified in "black calcite" associated with silver ores at the Aurora mine (Treasure Hill), Hamilton, Nevada. Specifically these are: (1) argentian chalcophanite (aurorite) (Ag 2 Ba,Ca,Pb,-K 2 ,Cu,Mn (super +2) )Mn 3 (super +4) O 7 . 3H 2 O; (2) argentian todorokite (Ag 2 ,K 2 ,Ca,Ba,-Na 2 ,Cu,Pb)Mn 4 (super +4) O 9 . 5H 2 O; and (3) hydrous silver-bearing lead manganese oxide (Pb,Cu,Ba,Sb,Ag 2 ,Ca,K 2 )Mn 5 (super +4) O 11 . 5H 2 O. Based on the large concentration of silver in argentian chalcophanite (7.50% Ag 2 O) and the low zinc content (0.25% ZnO) this mineral is recognized as a new species and named "aurorite."Physical and optical properties, and chemical analyses of the three minerals are presented together with X-ray powder diffraction data for aurorite and argentian todorokite. All chemical analyses were done with the electron microprobe analyzer. Due to extremely small particle size and textural relations, no X-ray powder data were obtained for the hydrous silver-bearing lead manganese oxide. Associated minerals include cryptomelane, pyrolusite, birnessite(?), cerargyrite, native silver, quartz, and manganoan calcite. Although the general uniform dark color of the "black calcite" and apparent uniform distribution of the inclusions suggests contemporaneous formation, examination of polished sections at high magnifications shows a definite paragenetic sequence. Manganoan calcite is replaced by fine-grained intergrowths of cryptomelane, pyrolusite, birnessite(?), and cerargyrite. Native silver formed early and the silver-bearing manganese oxides formed late in the sequence; aurorite fills microfractures that cut through all other minerals.These three silver-bearing manganese oxides were recognized only at the Aurora mine, Hamilton, Nevada, although black calcite veins were studied from numerous areas in the western United States. The geologic features of silver-bearing black calcites are described by Hewett and Radtke in the preceding paper.

Nevada↗