Formula: As4S3
Origin of name: From Greek for two forms, for the two forms in which this mineral was thought to occur
Crystal system: Orthorhombic
Crystal class: 2/m 2/m 2/m
Twinning:
Unit cell: a =11.24 Å, b = 9.90 Å, c = 6.56 Å
Colour: Orange-yellow
Diaphaneity: Transparent
Luster: Adamantine
Habit: Crystals dipyramidal, usually minute, groups of parallel crystals
Hardness: 1.5
Specific gravity: 3.58
Cleavage: None
Tenacity: Brittle
Streak:
Synonyms/varieties:
Comments: Burns without residue. Formed as deposits at fumarolic vents at temperatures of about 70-80°C, also formed in a ore deposit under secondary conditions
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