Tenacity
-
Brittle
Solubility
-
Soluble
Durability
-
-
Specific Gravity
3.355-3.4333.30-3.50
1
7.18
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Fracture
Uneven
Uneven, ConchoidalWalter Schumann, Conchoidal
Cleavage
{???} Good, {???} Good
Perfect on {110}, poor on {101}, {001} rare
Mohs Hardness
-99995
2
10
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Chemical Composition
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)
Zn 4Si 2O 7(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references