Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.03-3.182.90-2.98
1
7.18
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Fracture
Uneven, Irregular, Conchoidal
Conchoidal, ConchoidalWalter Schumann
Cleavage
{???} Indistinct
Distinct on {11 2 0}, imperfect on {10 1 1}
Mohs Hardness
7-7.57.5-8
2
10
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Chemical Composition
Na(Mg 3)Al 6(Si 6O 18)(BO 3) 3(OH) 3(OH)Gemdat.org , Management Team (2012)
Be 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references