Luster is metallic. Transparency crystals are opaque. Crystal System is isometric. Crystal Habits include small octahedral crystals, usually well formed, and as granular masses in sulfide rocks. Cleavage is imperfect.
Fracture is uneven.
Steak is black. A red to violet tarnish forms on weathered specimens. Best Field Indicators are crystal habit, streak, associations, tarnish and color.