Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
From the Greek for oblique and fracture, descriptive of the cleavage
(Na,K)AlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
(Na,Ca,K) 8(Si,Al) 12O 24(SO 4,Cl,CO 3) 3(H 2O)Arthur Thomas , Gemstones (2009)