Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Imperfect in one direction
CaCuAlSi 2O 6(OH) 3Michael OâDonoghue , Gems, Sixth Edition (2006)
Ca 5(PO 4) 3FAnthony et al , Handbook of mineralogy (2001)