A review of some aspects of the geochemistry and mineralogy of the Witwatersrand gold deposits.


Advances in science and technology in the past two decades have stimulated not only the growth of the mining industry, but also the geological sciences. The new techniques and instrumentation available for the analysis of trace and ultra-trace elements, as well as the development of the scanning electron microscope, have made possible the study of new aspects of the Witwatersrand gold and uranium deposits. These studies have greatly enhanced the knowledge of the distribution and origin of the gold within these deposits. This paper reviews the work that was carried out during the past ten years at the Chamber of Mines Research Organization. The geochemistry of the gold, and in particular the gold-to-silver ratio, can be used to identify distribution patterns and possible provenance areas. The morphological features of gold particles showed that relatively short transport distances of 30 to 50 km prevailed, which indicates that the original primary deposits were situated close to the basin in which deposition and concentration took place. The geochemistry of the quartz and pyrite pebbles and their fluid and associated mineral inclusions can delineate distribution patterns and supply information on the nature of the primary deposits. Hallbauer,-D.K. (Chamber of Mines Research Organisation, Transvaal (South Africa)).