Eclarite

Formula:   Pb₉(Cu,Fe)Bi₁₂S₂₈

Origin of name:   For Eberhard Clar, Austrian mineralogist

Crystal system:   Orthorhombic

Crystal class:   2/m 2/m 2/m

Twinning:

Unit cell: a = 54.76 Å, b = 4.030 Å, c = 22.75 Å

Colour:  Whitish gray

Diaphaneity:  Opaque

Luster:   Metallic

Habit:   Crystals, acicular, in fan-shaped aggregates to 1.5 cm; granular

Hardness:   2.5 to 3.5

Specific gravity:   6.85

Cleavage:   None

Tenacity: 

Streak: 

Synonyms/varieties:

Comments: Found in gold-bearing sulphide ores of copper located in quartz veins cutting amphibole-grade meta-mafic rocks. Hardness markedly anisotropic.