The Platinum Group Minerals in two parts of the Massive Sulphide Body of the Uitkomst Complex, Mpumalanga, South Africa

Abstract

Platinum Group Elements (dominated by palladium) are present in the Ni-Cu-Co bearing massive sulphide ore of the Uitkomst Complex, Mpumalanga Province, South Africa. Mineralogical investigations were conducted in two different parts of the ore body and it was found that these elements are contained in fine-grained mineral phases that are largely attributed to five mineral types based on composition and optical properties. Most of these phases fall within the quaternary system Pd-Bi-Te-Sb. Mineral assemblages of this composition are generally regarded as indicative of relatively low temperature (probably less than 490°C) conditions for the formation of the associated massive sulphide ores. Although the mineral phases reported are similar, there are significant differences in the relative abundances of individual mineral phases between the two areas. The distribution of the individual phases recorded for the deeper part of the ore body indicates an increase in Type II (michenerite) grains towards the base of the zone sampled, an antipathetic relationship between Type I (merenskyite) and Type II (michenerite) phases, and a concentration of Type III (testibiopalladite) grains at the top and the base of the zone. The Platinum Group Mineral grains are preferentially associated with pyrrhotite and generally located along grain boundaries. The relative abundances of the Platinum Group Elements in the massive sulphide body are similar to that of other Ni-sulphide deposits such as Sudbury and Noril’sk, but differ significantly from that of the Merensky Reef, UG-2 Reef, and Platreef ore bodies of the Bushveld Complex.