Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
SiO 2Ulrich Henn and Claudio C.