Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
SiO 2Walter Schumann , Gemstones of the world (2001)