Auricupride

Formula:  AuCu₃

Origin of name:  From composition (Latin aurum = gold and cuprum = copper)

Crystal system:  Cubic

Crystal class:  4/m -3 2/m

Twinning:

Unit cell: a = 3.753 Å (synthetic)

Colour:  Yellow with reddish tint

Diaphaneity: Opaque

Luster:  Metallic

Habit:  Tiny irregular grains, massive

Hardness:  3.5

Specific gravity: 11.5 (13.77 calculated)

Cleavage:  None

Tenacity:

Streak:

Synonyms/varieties:

Comments: Formed in serpentinites as the product of low temperature ordering and unmixing of Au-Cu solid solution alloys