Luster is metallic. Crystals are opaque. Crystal Habits include elongated prismatic to tabular crystals. Also lamellar, rarely massive. Cleavage is rather poor in one direction.
Fracture is conchoidal.
Streak is black. Deep longitudinal striations on most crystal faces. Associated Minerals are chalcopyrite , quartz , gold , siderite , calcite , pyrite , pyrrhotite and several copper sulfides . Best Field Indicators are crystal habit especially its twins, color, luster and occurrence.