Tenacity
Brittle
-
Solubility
-
-
Durability
-
-
Specific Gravity
2.60-2.655.2
1
7.18
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Fracture
Uneven, Conchoidal
Subconchoidal, Conchoidal
Cleavage
Perfect on {001}, very good on {010}, imperfect on {110}
Good in one direction
Mohs Hardness
6-6.56-6.5
2
10
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Chemical Composition
NaAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references