Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Subconchoidal, Uneven, Subconchoidal, Conchoidal, Brittle
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
NaAlSi 2O 6 · H 2OMichael OâDonoghue , Gems, Sixth edition (2006) More from other references