Tenacity
Brittle
Brittle
Solubility
-
Soluble
Durability
-
-
Specific Gravity
2.60-2.903.25-3.35
1
7.18
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Fracture
Uneven, Conchoidal, Irregular
Conchoidal, ConchoidalWalter Schumann
Cleavage
Imperfect on {0001}
Perfect in three directions
Mohs Hardness
7.5-85
2
10
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Chemical Composition
Be3Al2Si6O18
CuSiO 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references