Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
ConchoidalWalter Schumann
BeAlSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Ca 3Fe 2(SiO 4) 3Arthur Thomas , Gemstones (2009)