Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Perfect on {001}, imperfect on {110}
(K,Na)Ca4Si8O20(F,OH)•8(H2O)
{111} Indistinct, {111} Indistinct, {111} Indistinct
(Ca,Na) 2Ta 2O 6(O,OH,F)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references