Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.355-3.4332.79-2.87
1
7.18
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Fracture
Uneven
Conchoidal
Cleavage
{???} Good, {???} Good
{010} perfect; {100} good, interrupted; {101} indistinct; {001} in traces
Mohs Hardness
-99995.5-6
2
10
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Chemical Composition
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)
NaBePO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references