ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
SiO 2(+Al 2O 3)Walter Schumann , Gemstones of the world (2001)
(Be,Cs) 3Al 2Si 6O 18 · 0.5H 2OUlrich Henn and Claudio C.