Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.26-3.412.9-3.5
1
7.18
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Fracture
Fibrous, ConchoidalWalter Schumann
Conchoidal
Cleavage
Distinct on {100}, poor on {110}; parting on {001}
{110} Perfect, {???} Distinct, {???} Distinct
Mohs Hardness
7-8.55.5-6
2
10
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Chemical Composition
AlAl6O3BSi3O18
(Mg,Fe2+ ) 2(Mg,Fe2+ ) 5Si 8O 22(OH) 2Anthony et al , Handbook of mineralogy (2001)