Nichromite

Nichromite (Ni,Co,Fe)(Cr,Fe,Al)2O4 is a black cubic metallic mineral and member of the spinel group. Nichromite was originally reported from the Bon Accord nickel deposit in Barberton District, South Africa. Occurring naturally in a nickel deposit, nichromite is named for chromite with dominant nickel. The atomic arrangement of the spinel group is a commonly studied structure and characteristically has four closely packed oxygen atoms. The nickel atoms are organized corresponding to a "normal" spinel arrangement. The mineral has only been found in the Bon Accord Nickel Deposit in South Africa where it is formed by replacing chromite and rimmed by trevorite.