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A. S. Radtke

Publications and source records attributed to A. S. Radtke.

7 recordsLinked to original sources
USGS1983

Hydrothermal alteration of graywacke and basalt by 4 m NaCl

Separate experiments at 350 degrees C and 500 bars at a rock/fluid ratio of 1/10. Illite, dolomite, and quartz amounting to 67 percent of the original graywacke, were converted to albite and smectite. The rock gained Na and released Ca, K, heavy metals, and CO 2 to solution. In sharp contrast, the reaction of 4 m NaCl with basalt produced only minor alteration. Albitization of graywacke produces H (super +) whereas albitization of basalt apparently consumes H (super +) . All experiments to date that have reacted basalt with sea water, natural brine, and fully saturated NaCl over a variety of conditions have been unsuccessful in producing a spilite alteration assemblage.

Economic Geology↗
USGS1981

Spectroscopic geochemical study of vanadiferous marine sediments of the Gibellini claims, southern Fish Creek Range, Eureka County, Nevada

Samples of cuttings from three drill holes in the Gibellini claims were analyzed by emission spectroscopic techniques for a large suite of major and trace elements. Unoxidized siliceous "black shale" from drill hole NGA 7 is strongly enriched in Cd, Mo, Sb, Se, V, and Zn, and also contains relatively high concentrations of As, Ba, Cu, Ni, and Tl compared with nonmetalliferous shales. Analyses of 103 samples plotted against depth in drill holes NGA, NG31, and NGA7, and selected XRD data, show the following: 1. Groups of elements with distinct distribution patterns define most of major mineralogic components of the rocks. The "normal shale" component, which includes several detrital and authigenic phases, is indicated by covariations among Ti, Al, Fe, Na, Mg, K, B, Be, Co, Cr, Ga, La, Sc, Sr, and Zr. The shale component is diluted by varying amounts of the following minerals (and associated elements): silica (Si); dolomite (Mg, Ca, Mn, Sr); apatite (Ca, Be, Cr, La, Sr, Y); barite (Ba, Sr); sphalerite (Zn, Cd, Fe?); smithsonite (Cd, Co, Mn, Ni, Zn); bianchite (Cd, Ni, Zn) ; and bokite (V). Pyrite, gypsum, and jarosite were also identified. 2. The highly siliceous kerogenous metalliferous Gibellini facies is underlain by argillaceous and (or) dolomitic rocks. The transition zone deduced from the chemical data is not well defined in all instances, but probably represents the bottom of the black shale deposit. 3. Oxidation has reached to variable depths up to at least 150 ft, and has caused profound changes in the distributions of the enriched metals. Molybdenum, Se, and V have been partially removed from the upper parts of the sections and are concentrated near or slightly above the base of the Gibellini facies. Cadmium, Ni, and Zn have been strongly leached and now occur at or below the base of the Gibellini facies. The variable depth of oxidation, the redistribution and separation of the metals, and the complex mineralogy of the deposit may make development of the claim complicated.

Open-File Report↗
USGS1979

Metals in Devonian kerogenous marine strata at Gibellini and Bisoni properties in southern Fish Creek Range, Eureka County, Nevada

A kerogen-rich sequence of siliceous mudstone, siltstone, and chert as much as 60 m thick on ridge 7129 in the southern Fish Creek Range, referred to as Gibellini facies of the Woodruff Formation, has been evaluated on the surface and in drill holes principally for its potential resources of vanadium, zinc, selenium, molybdenum, and syncrude oil content. The strata are part of a strongly deformed allochthonous mass of eugeosynclinal Devonian marine rocks that overlie deformed allochthonous Mississippian siliceous rocks and relatively undeformed autochthonous Mississippian Antler flysch at this locality. The vanadium in fresh black rocks obtained from drill holes and fresh exposures in trenches and roadcuts occurs chiefly in organic matter. Concentrations of vanadium oxide (V2O5) in unoxidized samples range from 3,000 to 7,000 ppm. In oxidized and bleached rock that is prevalent at the surface, concentrations of vanadium oxide range from 6,000 to 8,000 ppm, suggesting a tendency toward enrichment due to surficial weathering and ground-water movement. Zinc occurs in sphalerite, and selenium occurs in organic matter; molybdenum appears to occur both in molybdenite and in organic matter. Concentrations of zinc in unoxidized rock range from 4,000 to 18,000 ppm, whereas in oxidized rock they range from 30 to 100 ppm, showing strong depletion due to weathering. Concentrations of selenium in unoxidized rock range from 30 to 200 ppm, whereas in oxidized rock they range from 200 to 400 ppm, indicating some enrichment upon weathering. Concentrations of molybdenum in unoxidized rock range from 70 to 960 ppm, whereas in oxidized rock they range from 30 to 80 ppm, indicating strong depletion upon weathering. Most fresh black rock is low-grade oil shale, and yields as much as 12 gallons/short ton of syncrude oil. Metahewettite is the principal vanadium mineral in the oxidized zone, but it also occurs sparsely as small nodules and fillings of microfractures in unweathered strata. In fresh rock, bluish-white opaline-like silica (chalcedonic quartz) fills microfractures, and is believed to have originated by diagenetic mobilization of opaline silica from radiolarian tests and sponge spicules. As revealed by microscopic study, the Gibellini facies originally consisted of siliceous muds, slimes, and oozes high in organic constituents. The organic matter is amorphous flaky and stringy sapropel, and probably includes remains of bacteria, phytoplankton, zooplankton, and minor higher plants. Recognizable organic remnants include radiolarian tests, sponge spicules, conodonts, brachiopod shells, algae, and humic debris. Diagnostic radiolarians indicate a Late Devonian age for the Gibellini facies of the Woodruff Formation. Some pyrite is disseminated through the rock and may be primary (syngenetic) but significant pyrite and marcasite occur in chalcedonic quartz veinlets and appear to be diagenetic. In fresh rock, black solid bitumen and liquid oil fill voids and microfractures. These early phase hydrocarbons probably were released during diagenesis from complex nonhydrocarbon molecular structures originating from living organisms, and formed without any major thermal degradation of the kerogen. Gas chromatographic analysis of the saturated hydrocarbon fraction indicates a very complex mixture dominated by branched and cyclic compounds. Conodont and palynomorph color alteration, vitrinite reflectance, and other organic geochemical data suggest that the organic matter in the rock is thermally immature and has not been subjected to temperatures greater than 60?C since deposition in Devonian time. All of these characteristics are consistent with the interpretation of a relatively low temperature and a shallow-burial history for the Gibellini facies on ridge 7129.

Open-File Report↗
USGS1967

Silver-bearing black calcite in western mining districts

The name black calcite has been applied from time to time to a dark gray to black variety of calcite or aragonite in metalliferous ore deposits in the Western States. Most of the material shows curved, roughly rhombic cleavage. The color is due to dispersed minute grains of one or more oxides of manganese, so dispersed that they rarely show any relation to cleavage surfaces or outward crystal forms.Recent study shows that the black calcite from numerous metalliferous deposits in the Western States contains small amounts of several metals, especially zinc, lead, and silver; in places, the crude black calcite contains as much as one percent silver and the black residue remaining after solution of the calcite as much as 1,500 ounces of silver to the ton. Black calcite is recognized in some deposits of Late Cretaceous to early Tertiary age where the host is Paleozoic carbonate rocks; thus far, this variety contains the larger amounts of silver. It is also present in some vein deposits where the host is generally volcanic rocks of middle Tertiary age; these are known in many districts in the southwest and even though the lead and zinc content is noteworthy, the silver content rarely exceeds one ounce to the ton (8).By studying polished sections of black calcite from the Aurora mine, White Pine County, Nevada, three silver-bearing manganate minerals have been recognized; (1) an argentian chalcophanite containing 7.5 percent silver (Ag 2 O), to which, in a following paper, the name aurorite is given; (2) argentian todorokite containing 3.9 percent silver (Ag 2 O), and (3) hydrous silver-bearing lead manganese oxide, containing 1.18 percent silver (Ag 2 O).

Nevada↗