Tenacity
Brittle
Brittle
Solubility
-
Soluble
Durability
-
-
Specific Gravity
3.3-3.53.30-3.50
1
7.18
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Fracture
Uneven
Uneven, ConchoidalWalter Schumann, Conchoidal
Cleavage
Perfect on [110]
Perfect on {110}, poor on {101}, {001} rare
Mohs Hardness
5-65
2
10
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Chemical Composition
NaNa2(Fe++4Fe+++)Si8O22(OH)2
Zn 4Si 2O 7(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references