Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Subconchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
(Cs,Na)(AlSi 2O 6) · 0.5H 2OWalter Schumann , Gemstones of the world (2001) More from other references
(Ca,Ce)(Al,Ti,Mg)12O19