Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
2.54-2.783.2-3.4
1
7.18
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Fracture
Conchoidal
Uneven
Cleavage
Good in three directions
Perfect on [001] imperfect on [100]
Mohs Hardness
5-63
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
(K,Na) 3(Fe2+ ,Mn) 7Ti 2Si 8O 24(O,OH) 7Anthony et al , Handbook of mineralogy (2001)