Abstract
M.Sc. (Geology)
Platinum-group minerals occurring in the P2 horizon at Lonmin’s Akanani Prospect on the Platreef of the Bushveld Complex in South Africa comprise (Pt,Pd)-bismuthotellurides, platinum-group element arsenides, ferroplatinum, Pt-Pd alloys and platinum-group element sulphides. The (Pt,Pd)-bismuthotellurides michenerite, moncheite, kotulskite and maslovite are the most abundant. An investigation into the mineral chemistry of the (Pt,Pd)-bismuthotellurides was conducted using a mineral liberation analyser and an electron microprobe. The (Pt,Pd)-bismuthotellurides typically occur in contact with primary silicates (such as feldspar, pyroxene and olivine), secondary silicates (such as serpentine, chlorite and grossular), oxides (magnetite), and base metal sulphides (pyrrhotite, pentlandite and chalcopyrite).
Most of the Pt-bismuthotellurides analysed belong to the maslovite (PtBiTe)-moncheite (PtTe2) series, in the form of a solid solution. Some of the Pd-bismuthotellurides correspond to the michenerite (PdBiTe) series while most compositions plot along the kotulskite (PdTe)-sobolevskite (PdBi) solid solution series. The mineral chemistry comparisons of the (Pt,Pd)-bismuthotellurides from Akanani (with other localities) demonstrate that other Bushveld Complex localities have similar trends to that of the Akanani Prospect, while other localities world-wide are characterised by a dominance of Pd-bismuthotellurides. This is likely a complex function of bulk composition, along with variations in e.g. temperature during crystallisation, and hydrothermal alteration.
M.Sc. (Geology)