Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Al 6B 5O 15(F,OH) 3Ulrich Henn and Claudio C.
CaTiSiO 5Ulrich Henn and Claudio C.