Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.43-3.445.6-5.76
1
7.18
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Fracture
-
Uneven
Cleavage
None Observed
[001] perfect; [100] distinct
Mohs Hardness
6.5-72.5-3
2
10
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Chemical Composition
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Pb 5Cu 2(SO 4) 3(CO 3)(OH) 6Anthony et al , Handbook of mineralogy (2001)