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