Location: |
Witwatersrand, Republic of South Africa |
Major Minerals: |
Pyrite, native gold, uraninite, thorian uraninite, carbonaceous material, uraniferous carbon (called thucholite), brannerite |
Minor Minerals: |
Arsenopyrite, cobaltite, galena, gersdorffite, pyrrhotite, bravoite, rutile, anatase, sphalerite, chromite, zircon |
Trace Minerals: |
Include Ir-Os-Ru alloys, iron-platinum alloys, monazite, xenotime, tennantite, stromeyerite |
Textures: |
Detrital minerals include zircon, chromite, ilmenite, magnetite, pyrite, arsenopyrite and gersdorffite; authigenic minerals include rutile, anatase, gersdorffite and bravoite. Pyrite occurs as rounded grains enclosing native gold, pyrrhotite and chalcopyrite. Thorian uraninite forms rounded to euhedral grains in conglomerates, uraninite occurs as euhedral crystals in hydrocarbons, elsewhere uranium occurs as coffinite and as uranium-titanium oxide intergrowths (uranium-leucoxene) comprising leucoxene, anatase and brannerite. Native gold forms small rounded grains associated with pyrite or 1-2µm grains associated with hydrocarbons where it is perhaps biogenic in origin. Remobilized gold is more abundant than detrital gold, but has not traveled far. |
References: |
Feather and Keen 1975; Feather, 1976; Hallbauer and Utter, 1977; Simpson and Bowles, 1977; Thiel et al., 1979; Clemmey, 1981; Saager et al., 1982; Smits, 1987 |