ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
ZrSiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.