Color is dark gray. Luster is metallic and silky. Transparency Crystals are opaque. Also in fiberous masses. Cleavage is good in one direction perpedicular to its length.
Fracture is uneven.
Associated Minerals include pyrite . sphalerite , galena , stibnite and arsenopyrite . Crystals are not flexible and are brittle. Best Field Indicators crystal habit, brittleness, associations, color and luster.