Abstract
Systematic relationships between the concentrations of Co, Ni, and Cu and the metal/sulphur ratio in pyrrhotite from the upper zone of the Bushveld Complex, South Africa were investigated. Due to the long cooling history of the Bushveld Complex, a very efficient exsolution of pentlandite and chalcopyrite from the pyrrhotite took place. Based on 3122 microprobe analyses of pyrrhotite coexisting with pentlandite over a stratigraphic interval of 676.5 m, and 1092 additional analyses from one sample it was possible to show that especially the concentrations of Co and Ni are very low compared to many values in the literature. A systematic decline in Co and Ni with increasing metal/sulphur ratio in pyrrhotite was observed, while no systematic relationship for Cu could be established.
