Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Conchoidal, Brittle, Metallic, Conchoidal, Handbook of mineralogy (2001)
Al 6B 5O 15(F,OH) 3Ulrich Henn and Claudio C.
(Mg,Fe2+ ) 3Si 2O 5(OH) 4Anthony et al , Handbook of mineralogy (2001)