ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Al 2Be 3Si 6O 18Martin H.
SiCArthur Thomas , Gemstones (2009)