Criddleite

Formula:  TlAg₂Au₃Sb₁₀S₁₀

Origin of name:  For Alan J. Criddle (1944- ), British mineralogist, British Museum (Natural History), London

Crystal system:  Monoclinic

Crystal class:  2 or m or 2/m

Twinning:

Unit cell: a = 19.96 Å, b = 8.057 Å, c = 7.809 Å, β = 92.08°

Color:  Gray blue (reflected light)

Diaphaneity:    Opaque

Luster:  Metallic

Habit:  Anhedral rims around aurostibite, native gold and native antimony to 30 - 75 μm, isolated grains

Hardness:  3 to 3.5

Specific gravity:  6.86

Cleavage:

Tenacity:

Streak:  Black

Synonyms/varieties:

Comments:  Identified in polished section as a primary hydrothermal mineral in a complex gold deposit