ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Al 2Be 3Si 6O 18Martin H.
Ca 5(PO 4) 3FAnthony et al , Handbook of mineralogy (2001)