Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.26-3.363.2-3.4
1
7.18
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Fracture
Conchoidal
Uneven
Cleavage
Good on {100}
Perfect on [001] imperfect on [100]
Mohs Hardness
6.5-73
2
10
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Chemical Composition
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
(K,Na) 3(Fe2+ ,Mn) 7Ti 2Si 8O 24(O,OH) 7Anthony et al , Handbook of mineralogy (2001)