Tenacity
Brittle
Brittle
Solubility
Soluble
insoluble
Durability
-
-
Specific Gravity
2.976.86-7.03
1
7.18
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Fracture
Uneven
Subconchoidal, Uneven, Conchoidal, Irregular
Cleavage
None observed
{100} imperfect, {110} indistinct; partings on {111} or {011}
Mohs Hardness
2.56-7
2
10
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Chemical Composition
Na 3AlF 6Ulrich Henn and Claudio C.
SnO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references