Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Perfect on {010} imperfect on {100}
Mg 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
KAl 2AlSi 3O 10(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references