Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
(Be,Cs) 3Al 2Si 6O 18 · 0.5H 2OUlrich Henn and Claudio C.
{0001}, {11 2 0} imperfect
Zn 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references