Tenacity
Brittle
Brittle
Solubility
-
insoluble
Durability
-
-
Specific Gravity
3.3-3.56.86-7.03
1
7.18
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Fracture
Uneven
Subconchoidal, Uneven, Conchoidal, Irregular
Cleavage
Perfect on [110]
{100} imperfect, {110} indistinct; partings on {111} or {011}
Mohs Hardness
5-66-7
2
10
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Chemical Composition
NaNa2(Fe++4Fe+++)Si8O22(OH)2
SnO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references