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)
Subconchoidal, Uneven, Conchoidal, Irregular
{100} imperfect, {110} indistinct; partings on {111} or {011}
SnO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references