Tenacity
Brittle
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.90-2.986.5-7.1
1
7.18
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Fracture
Conchoidal, ConchoidalWalter Schumann
Uneven, Conchoidal
Cleavage
Distinct on {11 2 0}, imperfect on {10 1 1}
Imperfect- [10 1 1]
Mohs Hardness
7.5-83.5-4
2
10
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Chemical Composition
Be 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Pb 5(PO 4) 3ClArthur Thomas , Gemstones (2009)