The mineralogy of the Pering zinc-lead deposit, Cape Province, with special reference to supergene alteration

Diagenetic, disseminated zinc-lead mineralization occurs in stromatolitic dolomite at Pering, approximately 160 km north-north-west of Kimberley in the Northern Cape Province. Semi-massive to massive sulphide accumulations, with a higher ratio of lead to zinc than that of the disseminated ore are probably the result of partial, differential remobilization. The ore has a low precious- and trace-metal content and is compositionally simple. Weathering of the upper part of the ore body has resulted in sulphide dissolution, dedolomitization of the host rock, and the formation of supergene minerals which include smithsonite, hydrozincite, cerussite, anglesite, secondary galena, desclozite, and calcite. The distribution of these minerals is explained in terms of changing pH/Eh environments. The mineral constituents of each sample were determined by x-ray diffractometry. Detailed textural studies, mineral identification, and semi-quantitative mineral analyses were performed on a scanning electron microscope with an energy dispersive x-ray spectrometer