Mineral inclusions in Fe-Pt solid solution from the alluvial ore occurrences of the Anabar basin (northeastern Siberian Platform)

This study is concerned with the typochemical features of heavy-concentrate platinum from diamond placers of the Mayat-Vodorazdel’nyi site in the Anabar River basin. Platinum occurs there as Fe-Pt solid solutions (ferroan platinum of Ru-Rh specialization, ~ 90%), as well as minor Pd- and Ir-ferroplatinum. Among PGE minerals, Os-Ir-Ru alloys and chengdeite are revealed. Inclusions of PGE minerals are thoroughly studied, and the scales of their spread, the composition of mineral phases, and the relations between them are determined. Ruthenium-containing high-Rh ferroplatinum bears a lot of inclusions of Rh-S composition: Rh-containing PGE thiospinels and sulfides and arsenides of Rh, Ru, and Pt. In low-Rh platinum, mineral inclusions are much scarcer and usually form other parageneses. The mineral compositions in the system Rh-S-Ru indicate to the existence of a long isomorphous series Rh3S4-Ru3S4, with the content of Ru3S4 reaching 15 at.%.