Tenacity
Brittle
-
Solubility
-
-
Durability
-
-
Specific Gravity
2.90-2.982.60-3.02
1
7.18
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Fracture
Conchoidal, ConchoidalWalter Schumann
-
Cleavage
Distinct on {11 2 0}, imperfect on {10 1 1}
Perfect
Mohs Hardness
7.5-8-9999
2
10
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Chemical Composition
Be 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Mg,Fe2+ ) 5Al(Si 3Al)O 10(OH) 8Anthony et al , Handbook of mineralogy (2001)