Dyscrasite

Formula:   Ag₃Sb

Origin of name:   From Greek for bad mixture or bad alloy

Crystal system:   Orthorhombic

Crystal class:   mm2

Twinning:   On {110}, repeated as pseudo-hexagonal aggregates

Unit cell: a = 3.008 Å, b = 4.828 Å, c = 5.214 Å

Colour:  Silvery white; tarnishes yellowish, gray or black

Diaphaneity: Opaque

Luster:   Metallic

Habit:   Crystals pyramidal; massive, granular, foliated

Hardness:   3.5 to 4

Specific gravity:   9.74

Cleavage:   3; {001} and {011} distinct, {110} imperfect

Tenacity:   Uneven fracture; sectile but brittle

Streak:   Silver-white

Synonyms/varieties:

Comments: Found in hydrothermal veins with other silver minerals both as a primary and secondary mineral