Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
LiAl(PO 4)(OH,F)Walter Schumann , Gemstones of the world (2001) More from other references
Be 3Al 2Si 6O 18Ulrich Henn and Claudio C.