Detrital pyrite in the Witwatersrand gold fields of South Africa; evidence from truncated growth banding

A proposed new type of arsenian pyrite: Composition, nanostructure and geological significance

“…Arsenic-bearing pyrite, known as arsenian pyrite, is widespread in low-temperature hydrothermal environments, especially sedimentary basins and mineral deposits (Wells and Mullens, 1973;MacLean and Fleet, 1989;Cook and Chryssoulis, 1990;Richards and Kerrich, 1993;Savage et al, 2000;Kolker et al, 2003). Almost all previous studies of these pyrites have documented a close relation between arsenic and sulfur.…”

Solubility of gold in arsenian pyrite

“…Arsenian pyrite is found in numerous geologic settings, from sedimentary basins to hydrothermal ore deposits, including Carlin-type and epithermal Au deposits (Wells and Mullen, 1973;MacLean and Fleet, 1989;Cook and Chryssoulis, 1990;Richards and Kerrich, 1993;Savage et al, 2000;Kolker et al, 2003). Apart from being an economically important host for Au, arsenian pyrite is of great environmental interest because its oxidative dissolution can release significant amounts of As and trace metals into the environment (Savage et al, 2000;Sidle et al, 2001;Kolker et al, 2003).…”

Detrital pyrite in Witwatersrand gold reefs: X‐ray diffraction evidence and implications for atmospheric evolution

“…Concretionary pyrite is associated with the siliciclastic matrix, and in some cases shows prominent pressure shadows of quartz and quartz replaced by chlorite. It clearly predates the peak of the hydrothermal/metamorphic alteration and was likely an early diagenetic product ( Hallbauer, 1986; MacLean and Fleet, 1989). Compact rounded pyrite occurs as ‘sand’ grains (e.g.…”

“…Pyrite was studied in polished sections colour‐stained with potassium permanganate in 1: 1 sulphuric acid ( Fig. 1; MacLean and Fleet, 1989; Fleet et al ., 1989 ) and by electron microprobe analysis. In addition, grains of compact rounded pyrite were removed from a polished section of ‘buckshot’ ore from the Hartbeesfontein mine using hydrofluoric acid, and investigated by scanning electron microscopy ( Fig.…”

“…The studied conglomerates comprise pebbles of vein quartz and minor chert and shale in a matrix of quartz, pyrite, pyrophyllite, chlorite, and muscovite. As in previous studies ( Ramdohr, 1958; Hallbauer, 1986; MacLean and Fleet, 1989), three texturally distinct varieties of pyrite are recognized: compact rounded, concretionary and idioblastic. Idioblastic pyrite is subordinate.…”