Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Perfect in one direction, indistinct in one direction
K2Na(Ca,Mn)2Ti[O|Si7O18(OH)]
{111} Indistinct, {111} Indistinct, {111} Indistinct
(Ca,Na) 2Ta 2O 6(O,OH,F)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references