Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Poor on {110} and {100} very poor on {001}
Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH)4
{111} Indistinct, {111} Indistinct, {111} Indistinct
(Ca,Na) 2Ta 2O 6(O,OH,F)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references