Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.26-3.362.54-2.61
1
7.18
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Fracture
Conchoidal
Uneven
Cleavage
Good on {100}
{001} Perfect, {010} Good
Mohs Hardness
6.5-76
2
10
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Chemical Composition
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
KAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)