Is a Nickel Arsenide often mixed with other sulfide minerals. In this case is Nickeline.The formula is Ni11As8. The color is gery-reddish with a metallic luster, very shiny when cut and polished and high specific gravity .Hardness is 5.
It comes from a type locality :Eisleben,Saxony-Anhalt,Germany.
Note:Small cavity on the pavillion.
Weight: 5.57 ct.