Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.26-3.413.2-3.4
1
7.18
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Fracture
Fibrous, ConchoidalWalter Schumann
Uneven
Cleavage
Distinct on {100}, poor on {110}; parting on {001}
Perfect on [001] imperfect on [100]
Mohs Hardness
7-8.53
2
10
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Chemical Composition
AlAl6O3BSi3O18
(K,Na) 3(Fe2+ ,Mn) 7Ti 2Si 8O 24(O,OH) 7Anthony et al , Handbook of mineralogy (2001)