Geology topics

John F. Slack

Publications and source records attributed to John F. Slack.

57 records · Page 4Linked to original sources

USGS1979

Geochemical analyses of rock, soil, and stream sediment samples from the Big Frog Wilderness Study Area, Polk County, Tennessee and Fannin County, Georgia

Semiquantitative spectrographic analyses for 31 elements and atomic absorption analyses for gold and zinc on 43 stream sediments, 5 panned concentrates, 65 soils, and 81 rock samples from the Big Frog Wilderness Study Area and vicinity, Polk County, Tennessee, and Fannin County, Georgia, are reported here in detail. Locations for all 194 samples are given in Universal Transverse Mercator (UTM) coordinates. Rocks analyzed include metasiltstone, metasandstone, metaconglomerate, slate, and vein quartz. The data contain no obviously anomalous values that might be related to economically recoverable mineralization.

Georgia, Tennessee↗

USGS1978

Premetamorphic hydrothermal origin of the Tungsten Queen vein, Hamme District, North Carolina, as indicated by mineral textures and minor structures

The Hamme Tungsten district is a 13-km long, 2-km wide, northeast-trending belt located in northern Vance County, North Carolina and southern Mecklenburg County, Virginia (Fig. 1). The district contains the largest quartz-wolframite-type vein deposits in the United States. Over 50 tungsten-bearing veins occur in this area (Espenshade, 1947), from which more than 1 million short ton units of WO 3 have been produced since World War II Mining terminated in 1971 after a sharp drop in the price of tungsten; currently, the district is inactive.

North Carolina, Virginia↗

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↗