The Fate of Platinum-Group Minerals in the Exogenic Environment—From Sulfide Ores via Oxidized Ores into Placers: Case Studies Bushveld Complex, South Africa, and Great Dyke, Zimbabwe

Research on platinum-group minerals (PGM) at Great Zimbabwe and the Bushveld Complex reveals that weathering processes do not significantly contribute to the formation of new PGM crystals or nuggets. Instead, the study finds that weathering primarily destroys unstable PGM carriers in sulfide ores, leading to the dispersion of soluble elements like Pt and Pd, rather than their concentration. The surviving PGM suite in alluvial sediments reflects a 'rest spectrum' of residual, detrital grains, with stable phases like sperrylite and Pt-Fe alloys increasing in proportion while others degrade. This challenges the notion of substantial authigenic PGM formation in supergene environments. The investigation combined mineralogical methods (reflected light microscopy) with advanced techniques (SEM, MLA, EPMA, LA-ICPMS) to analyze samples from underground, surface outcrops, and river sediments, providing a coherent model for PGM behavior during weathering.

Oberthür, T. (2018). The Fate of Platinum-Group Minerals in the Exogenic Environment—From Sulfide Ores via Oxidized Ores into Placers: Case Studies Bushveld Complex, South Africa, and Great Dyke, Zimbabwe. Minerals, 8(12), 581. https://doi.org/10.3390/min8120581