Tenacity
Brittle
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.7-3.35.00-5.30
1
7.18
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Fracture
Uneven, Even
Uneven, ConchoidalWalter Schumann, Conchoidal
Cleavage
Perfect on the {001}
None, may show partings on {0001} and {10 1 1}
Mohs Hardness
2.5-3.06
2
10
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Chemical Composition
K(Mg,Fe++)3[AlSi3O10(OH,F)2
Fe 2O 3Arthur Thomas , Gemstones (2009)