Rammelsbergite is a nickel with formula NiAs2. It forms metallic silvery to tin white to reddish orthorhombic, and is usually massive in form. It has a Mohs hardness of 5.5 and a specific gravity of 7.1.
It was first described in 1854 from its type locality, Germany chemist, Karl Friedrich August Rammelsberg
It occurs as a hydrothermal mineral in medium temperature veins, safflorite, native bismuth , domeykite