Tennantite
ID: 33
Tennantite
Chemical Formula
(Cu,Fe)₁₂As₄S₁₃
Hardness (Mohs)
3 - 4.5
Crystal System
Isometric
Streak
Black to brownish-black
Luster
Metallic
Diaphaneity
Opaque
Color
Steel-gray to iron-black
Crystal Habit / Mode of Occurrence
Isometric - Hextetrahedral; commonly tetrahedral crystals, often twinned; also massive, granular.
Fun Facts
Tennantite forms a solid solution series with tetrahedrite ((Cu,Fe)₁₂Sb₄S₁₃), where arsenic (in tennantite) substitutes for antimony (in tetrahedrite). Common Uses: Ore of copper and arsenic; minor source of silver.