Tenacity
Brittle
-
Solubility
-
-
Durability
-
-
Specific Gravity
2.60-2.653.25-3.45
1
7.18
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Fracture
Uneven, Conchoidal
Conchoidal, Uneven
Cleavage
Perfect on {001}, very good on {010}, imperfect on {110}
Good on {110}
Mohs Hardness
6-6.56.5
2
10
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Chemical Composition
NaAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
Mg 3Al 6(Si,Al,B) 5O 21(OH)Walter Schumann , Gemstones of the world (2001) More from other references