Tenacity
-
Brittle
Solubility
-
insoluble in water
Durability
-
-
Specific Gravity
2.50-2.805.00-5.20
1
7.18
👆🏻
Fracture
-
Uneven, Conchoidal, ConchoidalWalter Schumann
Cleavage
Perfect
Indistinct on {001}; partings on {011} and {111}
Mohs Hardness
5-6.56-6.5
2
10
👆🏻
Chemical Composition
Na 4(Al,Si) 12O 24Cl to Ca 4(Si,Al) 12O 24(CO 3,SO 4)Arthur Thomas , Gemstones (2009)
FeS 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references