ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Uneven, Gemstones of the world (2001) More from other references
ZrSiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references