Gersdorffite

gersdorffite

nickeline

cobaltite

maucherite

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Formula: NiAsS
Sulphide, cobaltite group, forms a series with cobaltite, and a complete solid solution with krutovite. (AM83.403)
Crystal System: Isometric
Specific gravity: 5.9 measured, 5.966 calculated
Hardness: 5½
Streak: Grey-black
Colour: Gray, grayish black, silver white, or tin white
Common impurities: Co,As,Bi,Fe,Co,Sb,Cu
Environments:

Hydrothermal environments

Gersdorffite occurs in hydrothermal vein deposits formed at moderate tempertures. (Webmin) Associated minerals include nickeline, nickelskutterudite, cobaltite, ullmannite, maucherite, löllingite, platinum group minerals, millerite, pyrite, marcasite, chalcopyrite and siderite. (HOM, Mindat)

At Ait Ahmane, Bou Azzer, Morocco, gersdorffite is embedded in calcite, sometime associated with nickelskutterudite and quartz. Crystals are often zoned, with the outer zone richer in cobalt. (MinRec 38.5.375)

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