Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
NaFe3+3Fe3+6(BO 3) 3Si 6O 18(O,OH) 4Anthony et al , Handbook of Mineralogy (2001)
Perfect on {010} imperfect on {100}
Mg 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)