Spinel structural group | formula = Ni3S4 | strunz = 02.DA.05 | dana = | symmetry = Isometric hexoctahedral H-M symbol: (4/m{overline|3}2/m) Space group: F d3m | unit cell = a = 9.48 Å; Z=8 | color = Pale to steel-gray | habit = As octahedral crystals, massive, granular to compact | system = Cubic | twinning = Twinning on {111} | cleavage = Indis... Found on http://en.wikipedia.org/wiki/Polydymite