ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Splintery, Conchoidal, Uneven, Splintery, Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001)
Be 3Al 2Si 6O 18Ulrich Henn and Claudio C.
SiO 2Arthur Thomas , Gemstones (2009)