Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Uneven, Subconchoidal, Uneven, Subconchoidal, Conchoidal, Brittle
Al 6B 5O 15(F,OH) 3Ulrich Henn and Claudio C.
NaAlSi 2O 6 · H 2OMichael OâDonoghue , Gems, Sixth edition (2006) More from other references