Tenacity
Brittle
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.33-2.375.85-6.15
1
7.18
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Fracture
ConchoidalWalter Schumann
Conchoidal
Cleavage
Perfect on {010}, good on {100}
Fair in four directions forming octahedrons
Mohs Hardness
7.53.5-4
2
10
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Chemical Composition
Be 2BO 3(OH)Ulrich Henn and Claudio C.
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references