Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
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
Uneven, Irregular, Conchoidal
Ca 3Al 2(SiO 4) 3-x(OH) 4x (x=0.2 to 1.5)Anthony et al , Handbook of mineralogy (2001)