Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
2.50-2.803.87-4.14
1
7.18
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Fracture
-
Subconchoidal, Conchoidal
Cleavage
Perfect
Poor on {120}, in traces on {001}
Mohs Hardness
5-6.55.5-6
2
10
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Chemical Composition
Na 4(Al,Si) 12O 24Cl to Ca 4(Si,Al) 12O 24(CO 3,SO 4)Arthur Thomas , Gemstones (2009)
TiO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references