Mindat Short Description
Cobaltite-Gersdorffite Series.
See also UM1989-01-AsS:CoFeNi.
Three polytypes, which are probably temperature-dependent, with P213 being the low form (gersdorffite), Pca21 (orthogersdorffite) the intermediate (metastable?) form, and Pa3 (paragers...
IMA Formula (from Mindat)
NiAsS