Witwatersrand deposits, South

Palaeoplacers are placer concentrations that have occurred in the geological past and which are preserved till the present by a cover of later sedimentary rocks. The Witwatersrand gold-uranium deposits (South Africa) and the uranium deposits at Blind River (Ontario, Canada) and Jacobina (Brazil) are the most important examples of palaeoplacers. 

Meyer, F.M., Robb, L.J., OberthOr, T., Saager, R. Stupp, H.D., 1990. Cobalt, nickel, and gold in pyrite from primary gold deposits and Witwatersrand reefs. South African Journal of Geology, 93, 70-82. 

Weathering, washing and transport of primary deposits formed alluvial deposits of platinum group metals. Platinum and other heavy metals and minerals were concentrated in clay and sand. Secondary deposits occur in the Urals and Colombia. Os-miridium, originally found in Russia, is nowadays mainly obtained along with secondary deposits of gold in Alaska and in Witwatersrand in South Africa. 

Hallbauer D. K. (1986) The mineralogy and geochemistry of Witwatersrand pyrite, gold, uranium and carbonaceous matter. In Mineral Deposits of Southern Africa (eds. C. R. Anhaeusser and S. Maske). Geological Society of South Africa, Johannesburg, SA, pp. 731—752. 

Classic quartz-pebble conglomerate districts are the Blind River-Elliot Lake district, Canada, and the Witwatersrand, South Africa. Similar deposits are known in Australia, Brazil, Finland, Algeria, India, the U.S.S.R. and the U.S.A. 

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