Gersdorffite is a nickel arsenic sulfide mineral with formula NiAsS. It is a mineral consisting of nickel sulphid and nickel arsenide, having a silver-white to steel-gray color and metallic luster. It was first described in 1843 and named for Johann von Gersdorff (1781–1849), owner of the nickel mine at Schladming, Austria the type locality. It occurs as euhedral to massive opaque, metallic grey-black to silver white forms.
Gersdorffite, which is named for Johann von Gersdorff, the owner of the mine at which it was found, is a very uncommon nickel mineral that belongs to the Cobaltite Group of minerals.
- Category: Mineral
- Formula: NiAsS
- Crystal system: cubic
- Density: 5.9 g/cm3 (Measured) and 5.966 g/cm3 (Calculated)
Gersdorffite belongs to a solid solution series with cobaltite, CoAsS. Antimony freely substitutes also leading to ullmannite, NiSbS. It has a Mohs hardness of 5.5 and a specific gravity of 5.9 to 6.33. It crystallizes in the isometric system showing diploidal symmetry.
- Color: silver white to steel gray
- Mohs scale hardness: 5-5.5
- Streak: grayish black
- Specific gravity: 5.6-6.2
- Luster: Metallic
- Transparency: Opaque
- Hardness: 5½ on the Mohs scale
- Tenacity: Brittle
- Cleavage: Perfect}
- Fracture: Irregular/Uneven
Occurrence: In hydrothermal vein deposits formed at medium temperatures.
Gersdorffite occurs as a hydrothermal vein mineral along with other nickel sulfides. Associated minerals include nickeline, nickel-skutterudite, cobaltite, ullmannite, maucherite, löllingite, platinum-group minerals, millerite, pyrite, marcasite, and chalcopyrite.
Association: Nickeline, nickel-skutterudite, cobaltite, ullmannite, maucherite, l¨ollingite, platinum-group minerals, millerite, pyrite, marcasite, chalcopyrite.