Tenacity
Brittle
Brittle
Solubility
Soluble
Soluble
Durability
-
-
Specific Gravity
3.10-3.203.30-3.50
1
7.18
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Fracture
Uneven, Conchoidal
Uneven, ConchoidalWalter Schumann, Conchoidal
Cleavage
Poor to good on (001)
Perfect on {110}, poor on {101}, {001} rare
Mohs Hardness
6-6.55
2
10
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Chemical Composition
(Mg,Fe) 5(SiO 4) 2(F,OH) 2Ulrich Henn and Claudio C.
Zn 4Si 2O 7(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references