ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, ConchoidalArthur Thomas, Gemstones (2009)
SiO 2 + H 2OUlrich Henn and Claudio C.
TiO 2Michael OâDonoghue , Gems, Sixth Edition (2006)