The compositionally diverse platinum-group minerals (PGM) from the Evander Goldfield, in the eastern part of the Witwatersrand Basin (South Africa), have been studied by a number of modern techniques including SEM, EMPA, N-TIMS and LA MC-ICP-MS. The characteristic feature of PGMs from Evander is an extensive presence of Ru and Os-rich alloys (i. e., Ru-Os-lr, Ru-Os-lr-Pt, Ru-lr-Pt, Ru-Pt), which prevail over iridium, Ru-Os sulfides, Pt-Fe, Pt-Ru-Fe and Pt-lr-Os alloys. Unradiogenic 187Os/188Os values are clearly indicative of a subchondritic mantle source of the platinum-group elements. Compositional and Os-isotope evidence suggest that the Os-rich alloy grains were formed under mantle conditions. The model 187Os/188Оs ages obtained for the main set of PGM (4.1-2.9 Ga, n = 108) imply that the PGM are detrital, supporting a scenario in which the majority of PGM were incorporated into the Witwatersrand basin by their release from Archean ultramafic or mafic source-rocks during weathering.