Abstract
Detrital and authigenic Ni-Co minerals from Witwatersrand and Pongola conglomerate horizons have been investigated by means of microanalytical techniques and ore microscopy. The results indicate that cobaltite is the major detrital Ni-Co mineral whereas the authigenic assemblage is made up of cobaltite, gersdorffite, millerite, pentlandite, tačekite, and breithauptite. The authigenic arsenosulfides, generally, have Co/Ni ratios < 1 whilst the reverse is the case for the detrital arsenosulfides. This finding is attributed to (1) differences in the mineralogical properties of the various arsenosulfides, and (2) differences in the geochemical environments in which the detrital and authigenic minerals crystallized The data of the present study is in accordance with the modified placer theory for the formation of Precambrian conglomerate ores. Furthermore, the results indicate that earlier proposed temperatures of 400°–600 °C did not prevail during the crystallization of the authigenic minerals.
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Saager, R., Oberthür, T. (1984). Nickel-Cobalt Sulfides in Precambrian Gold and Uranium-Bearing Quartz-Pebble Conglomerates of South Africa. In: Wauschkuhn, A., Kluth, C., Zimmermann, R.A. (eds) Syngenesis and Epigenesis in the Formation of Mineral Deposits . Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-70074-3_23
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DOI: https://doi.org/10.1007/978-3-642-70074-3_23
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