Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Ca 2Al 3(SiO 4) 3(OH)Walter Schumann , Gemstones of the world (2001) More from other references
{110} good, 100 moderate, parting on {092} and {011}
TiO 2Michael OâDonoghue , Gems, Sixth Edition (2006)