Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.315.5
1
7.18
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Fracture
-
Conchoidal
Cleavage
Indiscernible
{111} Indistinct, {111} Indistinct, {111} Indistinct
Mohs Hardness
-99995-5.5
2
10
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Chemical Composition
NaFe 3+ 3 Al 6 (BO 3 ) 3 Si 6 O 18 (O,F,OH) 4 Anthony et al, Handbook of mineralogy (2001)
(Ca,Na) 2Ta 2O 6(O,OH,F)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references