Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.54-2.783.50-3.60
1
7.18
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Fracture
Conchoidal
Uneven
Cleavage
Good in three directions
Good on {110}, (110) ^ (1 1 0) ≈87°; parting on {100}
Mohs Hardness
5-66
2
10
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Chemical Composition
K(Ca,Na) 2Si 4O 10(OH,F) · H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Na,Fe,Ca)Si 2O 6Ulrich Henn and Claudio C.