Tenacity
Brittle
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.90-2.982.7-3.3
1
7.18
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Fracture
Conchoidal, ConchoidalWalter Schumann
Uneven, Even
Cleavage
Distinct on {11 2 0}, imperfect on {10 1 1}
Perfect on the {001}
Mohs Hardness
7.5-82.5-3.0
2
10
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Chemical Composition
Be 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
K(Mg,Fe++)3[AlSi3O10(OH,F)2