Tetrahedrite - Cu₁₂Sb₄S₁₃

Habit: Flint-gray to iron-black to dull black massive, compact or granular. Metallic, commonly splendent; opaque except in very thin fragments.

Environment: Probably the most common sulfosalt mineral, occurs in Hydrothermal veins and contact-metamorphic deposits

Etymology: Named for the tetrahedral crystal shape.