Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
70% SiO2, Al2O3, Na2O, K2O
Uneven, ConchoidalWalter Schumann, Conchoidal
Perfect on {110}, poor on {101}, {001} rare
Zn 4Si 2O 7(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references