Tenacity
Brittle
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.69-3.813.31
1
7.18
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Fracture
Uneven, Conchoidal to uneven, ConchoidalWalter Schumann
-
Cleavage
Distinct on {110}, imperfect on {010}, poor on {001}
Indiscernible
Mohs Hardness
8.5-9999
2
10
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Chemical Composition
BeAl 2 O 4
NaFe 3+ 3 Al 6 (BO 3 ) 3 Si 6 O 18 (O,F,OH) 4 Anthony et al, Handbook of mineralogy (2001)