Gersdorffite

Formula:  NiAsS

Origin of name:  For the von Gersdorffs mine owners, Schladming, Germany

Crystal system:  Cubic

Crystal class:  23

Twinning:

Unit cell: a = 5.65 Ǻ

Colour:  Tin-white to steel-gray, tarnishes gray or grayish black

Diaphaneity:  Opaque

Luster:  Metallic

Habit:  Crystals octahedral, cubo-octahedral, pyritohedral; faces often striated like Pyrite; massive, granular

Hardness:  5.5

Specific gravity:  5.9

Cleavage:  1; {001} perfect

Tenacity:

Streak:

Synonyms/varieties:

Comments:  Data are for gersdorffite-Pa3; there are also -P2/13 and -Pca2/1 polytypes