Formula: Ag8(Sb,As)Te2S3
Origin of name: For Benjamin Franklin Leonard (1921- ), American geologist, of the U.S. Geological Survey, Denver
Crystal system: Tetragonal
Crystal class: 4/m 2/m 2/m
Twinning: According to some simple law
Unit cell: a = 6.603 Å, b = 6.603 Å, c = 12.726 Å
Colour: Pale blue in reflected light
Diaphaneity: Opaque
Luster: Metallic
Habit: Black powdery crusts, grains, to 40 µm forming monomineralic crusts <1 mm across, lath-like grains 5-20 µm long
Hardness: 3
Specific gravity: 7.76
Cleavage: None
Tenacity:
Streak:
Synonyms/varieties:
Comments: Found as powdery crusts with other sulfides in fractures in an intensely silicified rhyolitic vitrophyre
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