Uneven, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Even
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Perfect {010} imperfect {100}
{111} Indistinct, {111} Indistinct, {111} Indistinct
Ca2Al3(SiO4)3(OH)
(Ca,Na) 2Ta 2O 6(O,OH,F)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references