Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.50-2.802.90-2.98
1
7.18
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Fracture
-
Conchoidal, ConchoidalWalter Schumann
Cleavage
Perfect
Distinct on {11 2 0}, imperfect on {10 1 1}
Mohs Hardness
5-6.57.5-8
2
10
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Chemical Composition
Na 4(Al,Si) 12O 24Cl to Ca 4(Si,Al) 12O 24(CO 3,SO 4)Arthur Thomas , Gemstones (2009)
Be 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references