Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.25-3.285.5
1
7.18
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Fracture
Uneven
Conchoidal
Cleavage
{100} Distinct, {001} Poor, {110} Poor
{111} Indistinct, {111} Indistinct, {111} Indistinct
Mohs Hardness
6.5-75-5.5
2
10
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Chemical Composition
Ca2Fe++Al2BO3Si4O12(OH)
(Ca,Na) 2Ta 2O 6(O,OH,F)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references