Sulfides: Tetrahedrite-tennantite

Composition: Cu₁₂Sb₄S₁₃-Cu₁₂As₄S₁₃; iron may substitute for copper and silver for antimony; the name tetrahedrite is used when antimony predominates and tennantite when arsenic predominates (specialised characterisation is required to differentiate these minerals)

Crystal system: Isometric; typically massive

7.14.1
tetrahedrite crystals with quartz
Peru

Properties:

• Metallic lustre
• Greenish-grey to black color
• Dark streak (grey-black)
• Knife scratches easily (Mohs Hardness 3.5-4)
• High density
• No cleavage
• Uneven fracture
• Not ferromagnetic
• Does not react with hydrochloric acid (HCl)

Occurrence:

Tetrahedrite-tennantite occur with sulfides in hydrothermal vein and replacement ore deposits.

7.14.2 tetrahedrite crystals with quartz Peru	7.14.3 tetrahedrite crystals with quartz Peru

Tetrahedrite is more common than tennantite and is a significant source of copper, antimony and on occasion silver.