Nickeline
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Nickeline or niccolite is a mineral consisting primarily of nickel arsenide. The naturally-occurring mineral contains roughly 43.9% nickel and 56.1% arsenic by mass, but composition of the mineral may vary slightly. Wikipedia
Color: Pale copper red with blackish tarnish. white with strong yellowish pink hue on polished section strongly anisotropic
Unit cell: a = 3.602 Å, c = 5.009 Å; Z = 2
Cleavage: Imperfect,, Imperfect
Crystal class: Dihexagonal dipyramidal (6/mmm); H-M symbol: (6/m 2/m 2/m)
Crystal habit: Massive columnar to reniform, rarely as distorted, horizontally striated,, terminated crystals
Crystal system: Hexagonal
Diaphaneity: Opaque