Formula: Ir5Fe10S16
Sulphide of iridium and iron, kuvaevite group
Specific gravity: 6.30 calculated
Colour: Grey to brownish grey

Placer deposits

Tamuraite is a new mineral, approved in 2020 and to date (June 2022) reported only from the type locality.


At the type locality, the River Ko placer deposit, Sisim Placer Zone, Lysanskiy dunite-peridotite-gabbro complex, Krasnoyarsk Krai, Russia, tamuraite was found in a placer, as part of a heavy-mineral fraction recovered from the river. Grains of tamuraite form part of roundish composite inclusions of sulphide minerals rich in platinum-group elements; the polymineralic inclusions are hosted by osmium-iridium alloy grains. It is suggested that tamuraite formed at an advanced stage of crystallisation in sulphur in droplets of a residual melt. These droplets were enriched in sulphur, iron, nickel, copper and rhodium, and these elements were incompatible during the formation of the osmium-iridium alloy lode zones (AM 107.779).
Tamuraite is typically intergrown with rhodium-rich pentlandite and iridium-bearing members of the lauriteerlichmanite series (Mindat).

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