Antimonpearceite

Formula:(Ag, Cu)₁₆(Sb, As)₂S₁₁

Origin of name:  From its compositional relationship to pearceite

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning: On {110}

Unit cell: a = 12.81 Å, b = 7.41 Å, c = 11.91 Å, β = 90°

Colour:  Black

Diaphaneity: Opaque

Luster:  Submetallic

Habit:  Crystals are thin, tabular, pseudo-hexagonal to 2cm, in subparallel and rosette-like groups

Hardness:  3

Specific gravity:  6.34

Cleavage: None

Tenacity: Brittle

Streak:  Black

Synonyms/varieties:

Comments:  Dimorphous with polybasite. In epithermal precious metal veins.