Tenacity
Brittle
-
Solubility
-
-
Durability
-
-
Specific Gravity
2.90-2.982.30-2.50
1
7.18
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Fracture
Conchoidal, ConchoidalWalter Schumann
Uneven
Cleavage
Distinct on {11 2 0}, imperfect on {10 1 1}
Perfect on (001)
Mohs Hardness
7.5-84.5-5
2
10
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Chemical Composition
Be 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
KCa 4Si 8O 20(F,OH) · 8H 2OUlrich Henn and Claudio C.