Formula: CaAlSiO4(OH)
Origin of name: for Marc Bernard Vuagnat (1922-), Swiss professor of geology, University of Geneva
Crystal system: Orthorhombic
Crystal class: 222
Twinning:
Unit cell: a = 7.055, b = 8.542, c = 5.683
Colour: Colourless, white, light pink
Diaphaneity: Transparent to translucent
Luster: Vitreous
Habit: Crystals elongated along c-axis, highly modified, rarely as diphenoidal crystals, anhedral to subhedral , rarely euhedral
Hardness: 6
Specific gravity: 3.20 to 3.25
Cleavage: None
Tenacity: Brittle, conchoidal fracture
Streak: White
Synonyms/varieties:
Comments:
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