Tetrahedrite
Chemical Formula	(Cu,Fe)12Sb4S13
Species	Sulfides
Crystal System	Isometric
Mohs Scale	3-4
Specific Gravity	4.97
Color	Steel gray to iron-gray
Streak	Black, brown to dark red
Luster	Metallic
Refractive Index	n greater than 2.72
Diaphaneity	Opaque
Cleavage	None
Fracture	Sub-Conchoidal
Crystal Habit：Groups of tetrahedral crystals; massive, coarse to fine compact granular
Geological Setting：Low to moderate temperature hydrothermal veins and contact metamorphic deposits.