Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Uneven, Uneven, Irregular, Management Team (2012), Conchoidal, Brittle
Al 6B 5O 15(F,OH) 3Ulrich Henn and Claudio C.
Ca 3Al 2(SiO 4) 3-x(OH) 4x (x=0.2 to 1.5)Anthony et al , Handbook of mineralogy (2001)