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
Poor on {110} and {100} very poor on {001}
Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH)4