Images
Formula: IrAsS
Sulphide, iridium- and arsenic-
bearing mineral, cobaltite group, forms a series with
hollingworthite
Crystal System: Isometric
Specific gravity: 11.92 calculated
Hardness: 6½
Colour: Iron-black
Common impurities: Other elements such as Rh, Pd, Os, Ni and Co have been reported to replace Ir
Environments
Irarsite occurs as rims around platinum group alloys.
Associated minerals include platinum,
ruthenian
hollingworthite,
sperrylite, laurite,
iridarsenite,
ruthenarsenite,
rutheniridosmine,
chalcopyrite, chalcocite,
pyrrhotite, cobaltite,
gersdorffite,
pentlandite, nickeline,
magnetite, chromite and
olivine
(HOM).
Localities
At Pletena, Satovcha Municipality, Blagoevgrad Province, Bulgaria, irarsite occurs as inclusions in
chrompicotites
(HOM).
The type locality, the Onverwacht Mine, Steelpoort, Fetakgomo Tubatse Local Municipality, Sekhukhune District
Municipality, Limpopo, South Africa, is a platinum group element
mine in a hortonolite-dunite
body. Irarsite occurs in chromite in the
hortonolite-dunite,
intergrown with native platinum and with
ruthenian
hollingworthite
(AM 52.1579-1589).
Irarsite occurs rimming rutheniridosmine nuggets and as
inclusions which generally decrease in size and abundance towards the centre of the individual grains
(CM 12.280-284).
Back to Minerals