Tenacity
Brittle
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.60-2.655.6-5.76
1
7.18
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Fracture
Uneven, Conchoidal
Uneven
Cleavage
Perfect on {001}, very good on {010}, imperfect on {110}
[001] perfect; [100] distinct
Mohs Hardness
6-6.52.5-3
2
10
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Chemical Composition
NaAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
Pb 5Cu 2(SO 4) 3(CO 3)(OH) 6Anthony et al , Handbook of mineralogy (2001)