Formula: Pb8(As2O5)2OCl6
Origin of name: For George Gebhard, discoverer of mineral
Crystal system: Monoclinic
Crystal class: 2/m
Twinning:
Unit cell:
Colour: Brown
Diaphaneity: Transparent
Luster: Adamantine
Habit: Crystals acicular, to 2 mm length
Hardness: 3
Specific gravity: 6.0
Cleavage: 2; {001} perfect, {010} good
Tenacity:
Streak: White
Synonyms/varieties:
Comments: In cold HCl or HNO3 forms tiny octahedra of As2O3
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