Genkinite

genkinite

sperrylite

ruthenarsenite

stibiopalladinite

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Formula: Pt4Sb3
Alloy of platinum and antimony
Specific gravity: 9.256 calculated
Hardness: 5½ to 6
Colour: Pale brown or yellowish tan
Common impurities: Rh,Ni,Cu,Bi,As
Environments

Plutonic igneous environments
Placer deposits

Genkinite occurs in platinum bearing ophiolites or ultramafics and derived placers (Mindat).

Localities

At the type locality, the Onverwacht mine, Steelpoort, Fetakgomo Tubatse Local Municipality, Sekhukhune District Municipality, Limpopo, South Africa, genkinite occurs in the platinum deposit as irregular grains ranging in size from less than 5 microns to about 165 microns. It is associated with sperrylite, platinum - iron - copper - nickel alloys, platarsite, ruthenarsenite, stibiopalladinite, mertieite and an unidentified platinum - palladium - rhodium oxide in a sample containing silicates and chromite (CM 15.389-392).

At Harold's Grave Quarry, Unst, Shetland, Scotland, UK, genkinite has been located in two chromite-rich rocks from an ophiolitic environment. In one it forms part of a composite cluster of minerals, whereas in the other it is situated in a cluster of platinum group minerals but is isolated from them by silicate matrix. In both cases the genkinite forms irregular crystals with dimensions of approximately 12 x 4 microns and 8 x 2 microns (CM 26.979-990).

At Southern beach placer, Tugidak Island, Kodiak Island Borough, Alaska, USA, both genkinite and stibiopalladinite were found in one isoferroplatinum grain where they are associated with coeval zoned irarsite and hollingworthite; genkinite and stibiopalladinite are unzoned. The genkinite forms subhedral crystals up to 7 microns in length (CM 59.667-712).

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