Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.54-2.783.69-3.81
1
7.18
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Fracture
Conchoidal
Uneven, Conchoidal to uneven, ConchoidalWalter Schumann
Cleavage
Good in three directions
Distinct on {110}, imperfect on {010}, poor on {001}
Mohs Hardness
5-68.5
2
10
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Chemical Composition
K(Ca,Na) 2Si 4O 10(OH,F) · H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
BeAl 2 O 4