Calaverite

Formula:  AuTe₂

Origin of name:  After locality; Calaveras Co., California

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:   Common on {010}, {310}, or {111}

Unit cell: a = 35.96 Ǻ, b = 4.41 Ǻ, c = 16.81 Ǻ, β = 115.3°

Colour:  Brass-yellow to silver-white

Diaphaneity: Opaque

Luster:  Metallic

Habit:  Crystals lath-like or bladed, short prisms striated parallel to elongation; massive, granular

Hardness: 2.5 to 3

Specific gravity:  9.10 to 9.40

Cleavage:  None

Tenacity:  Subconchoidal to uneven; brittle

Streak:  Greenish to yellow

Synonyms/varieties:

Comments:  Dimorphous with krennerite. Found usually in veins in low-temperature hydrothermal deposits, but also in higher temperature deposits