ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Uneven, Uneven, Conchoidal, Uneven, Gems, Sixth Edition (2006)
{111} Indistinct, {111} Indistinct, {111} Indistinct
Perfect on {001}, good on {010}
(K,Cs)Al 4Be 4(B,Be) 12O 28Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Na,Ca)Al1-2Si3-2O8