ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001)
Al 2(PO 4)(OH) 3Michael OâDonoghue , Gems, Sixth Edition (2006)
Mg 2Al 4Si 5O 18Ulrich Henn and Claudio C.