Tenacity
Brittle
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.095.00-5.30
1
7.18
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Fracture
Uneven
Uneven, ConchoidalWalter Schumann, Conchoidal
Cleavage
Perfect on {100} and {010}, imperfect on {101}
None, may show partings on {0001} and {10 1 1}
Mohs Hardness
86
2
10
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Chemical Composition
CaAl2Si2O7(OH)2.H2O
Fe 2O 3Arthur Thomas , Gemstones (2009)