Tenacity
Brittle
Brittle
Solubility
Soluble
Soluble
Durability
-
-
Specific Gravity
2.783.30-3.50
1
7.18
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Fracture
Conchoidal
Uneven, ConchoidalWalter Schumann, Conchoidal
Cleavage
Perfect on {10 1 }; parting on {010}
Perfect on {110}, poor on {101}, {001} rare
Mohs Hardness
3.55
2
10
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Chemical Composition
K2Ca2Mg(SO4)4·2H2O
Zn 4Si 2O 7(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references