ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
CaTiSiO 5Ulrich Henn and Claudio C.
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references