Athabascaite

Formula:  Cu₅Se₄

Origin of name:  After locality; Lake Athabasca, Saskatchewan, Canada

Crystal system:  Orthorhombic

Crystal class:  Unknown

Twinning:

Unit cell: a = 8.227 Å, b = 11.982 Å, c = 6.441 Å

Colour:  Light gray to white

Diaphaneity: Opaque

Luster:  Metallic

Habit:  Microscopic elongated lath-like grains

Hardness:  2.5

Specific gravity:  6.59 (calculated)

Cleavage:  None

Tenacity:

Streak:

Synonyms/varieties:

Comments: Found as inclusions in and replacements of umangite, as stringers and veinlets in carbonate veins cutting basalt