Compositional variations in platinum-group minerals and gold, Konder alkaline-ultrabasic massif, Aldan Shield, Russia

The platinum-group minerals (PGM) of the Konder zoned alkali-ultrabasic massif, located east of the Aldan Shield, in far-eastern Russia, are predominantly represented by isoferroplatinum of two generations, both with Fe contents ranging from 7.5 to 11.5 wt.%. A high-temperature isoferroplatinum is saturated with platinum-group-element (PGE) impurities: up to 5.3 Ir, 2.9 Os, and 1.8 Rh (all in wt.%). In contrast, the later isoferroplatinum contains lower levels of Ir, Os and Rh: less than 1.9 Ir, 1.0 Os, 0.6 Rh (in wt.%). The minor PGM are represented by a wide range of solid solutions in the system Os-Ir-Rh-Pt, tetraferroplatinum, tulameenite, hongshiite, minerals of erlichmanite-laurite and irarsite-hollingworthite series, sperrylite, bismuthides, antimonides, tellurides, stannides, and hydroxides. There are possibly new mineral species: native ruthenium, the Pd-dominant analogue of hongshiite, Pt2As3, the Pt-dominant analogue of konderite and inaglyite, and others minerals, which form rims around grains of isoferroplatinum and inclusions in it. A similar morphology and distribution as found with Pt3Fe are observed with gold, related to rare lenses of sulfide and impregnations in dunite (Cu-, Pt-, and Pd-bearing high-grade gold) and monzodiorite cutting dunite (low-impurity middle- and low-grade gold).