A dimorph is a set of two minerals that share the same chemistry but have different structures. Not quite an exact dimorph with the addition of the nickel, but safflorite often contains traces of nickel, just not as much. Twinning is common in safflorite and forms star shaped trillings. Cobalt minerals are sometimes interesting to collect and safflorite is certainly interesting. Luster is metallic.
Crystals are opaque.
Also compact and massive. Twins are seen as star shaped trillings. Cleavage is indistinct. Streak is a black. Associated Minerals include arsenic , cobaltite , arsenopyrite , skutterudite , calcite and erythrite .