Formula: hydrous iron arsenate sulfate
Origin of name: from Greek for pitch
Crystal system: amorphous
Crystal class:
Twinning:
Unit cell:
Colour: light to dark brown, yellow, gray, whitish
Diaphaneity: transparent to opaque
Luster: vitreous, greasy, dull
Habit: opaline crusts, coatings, stalactitic, reniform, botryoidal, earthy
Hardness: 2 to 3
Specific gravity: 2.2 to 2.5
Cleavage: none
Tenacity:
Streak: yellow to white
Synonyms/varieties:
Comments: inadequately described, formula not definite
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