Argentotennantite

Formula:  (Ag, Cu)₁₀ (Zn, Fe)₂ (As, Sb)₄S₁₃

Origin of name:  From silver (Latin argentum), its chemical composition and by analogy to tennantite

Crystal system:  Cubic

Crystal class:  -43m

Twinning:

Unit cell: a = 10.584 Å

Colour:  Grey-black

Diaphaneity: Opaque

Luster:  Resinous

Habit:  Small grains to 0.1 mm

Hardness:  3.4 to 3.5

Specific gravity:  5.05 (calculated)

Cleavage:  None

Tenacity:

Streak:  Red-brown to black

Synonyms/varieties:

Comments:  Series with tennantite and freibergite. In polymetallic deposit.