They have some very similar properties such as a gray color, high density, low hardness, metallic luster, dark gray to black streaks and a similar environment of formation. Most form from hydrothermal fluids that crystallize at lower temperatures than other sulfides. They can be distinguish only by differences in their respective crystal habits, cleavages, fracture and x-ray techniques. Color is lead gray to black. Luster is metallic.
Crystals are opaque.
Crystal Habits include common acicular to prismatic, granular and even some fibrous crystals and massive forms. Streak is steel gray. Associated Minerals include calcite , galena , sphalerite , tetrahedrite , arsenopyrite and several other sulfosalts. Best Field Indicators are crystal habit, associations, cleavage, locality and density.