Tamuraite

tamuraite

pentlandite

laurite

erlichmanite

Images

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

Placer deposits

Tamuraite is a new mineral, approved in 2020 and to date (June 2023) reported only from the type locality.

Localities

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 laurite–erlichmanite series (Mindat).

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