Aikinite

Formula: PbCuBiS₃

Origin of name:  for Arthur Aikin (1773-1854), a founder of the Geological Society of London, England

Crystal system:  Orthorhombic

Crystal class:  2/m 2/m 2/m

Twinning:

Unit cell: a = 11.638 Å, b = 4.039 Å, c = 11.319 Å

Colour:  Blackish gray;  tarnishes brown or copper-red

Diaphaneity: Opaque

Luster:  Metallic

Habit:  Crystals prismatic to acicular, striated parallel to elongation

Hardness:  2 to 2.5

Specific gravity:  7.07

Cleavage:  1; {010} indistinct

Tenacity: 

Streak:  Grayish black

Synonyms/varieties:

Comments: Found in hydrothermal veins with gold, pyrite, galena, tennantite, enargite, chalcopyrite, quartz