Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
Na 8Al 6Si 6O 24(SO 4) · H 2OAnthony et al , Handbook of Mineralogy (2001)