NICKELINE
Nickeline (a.k.a. niccoline, niccolite) is a
nickel arsenide mineral - NiAs. It has a metallic luster, a metallic
pinkish-orange to pale copper color that tarnishes gray, and a gray
streak. Nickeline is fairly heavy for its size, is moderately hard (H=5
to 5.5), and has no cleavage. It tends to occur with some Ni-Fe-Cu
sulfide/arsenide minerals and with some Co-Ag minerals.
Nickeline (field of view ~1.7 cm across)