It occurs as euhedral to massive opaque, metallic grey-black to silver white forms.

Gersdorffite belongs to a solid solution series with cobaltite, CoAsS.

Antimony freely substitutes also leading to ullmannite, NiSbS.

[1] Gersdorffite occurs as a hydrothermal vein mineral along with other nickel sulfides.

Gersdorffite was first described in 1843 and named in 1845 for Johann von Gersdorff (1781–1849), owner of the nickel mine at Schladming, Austria the type locality.