Tenacity
Brittle
Brittle
Solubility
-
Dilute acid
Durability
-
-
Specific Gravity
1.792.93-2.96
1
7.18
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Fracture
Irregular/uneven
Subconchoidal, Conchoidal
Cleavage
Perfect on {10bar10}
Distinct on {010}, imperfect {110} and {011}
Mohs Hardness
2.53.5-4
2
10
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Chemical Composition
Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12•26(H2O)
CaCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references