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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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