Tenacity
Brittle
Brittle
Solubility
Soluble
-
Durability
-
-
Specific Gravity
2.754.32-4.48
1
7.18
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Fracture
Uneven, Conchoidal
Uneven, Subconchoidal, Conchoidal
Cleavage
Imperfect on {110}
{101}, good; {010}, poor
Mohs Hardness
5.53.5
2
10
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Chemical Composition
(Na,Ca) 8Al 6Si 6O 24(SO 4,S,Cl) 2Ulrich Henn and Claudio C.
Zn 2(AsO 4)(OH)Michael OâDonoghue , Gems, Sixth edition (2006)