Gems, Sixth Edition (2006)
Sub-Conchoidal, Irregular/uneven, Sub-Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Quartz: SiO2 Rutile: TiO2
(Li,Na)Al(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth edition (2006) More from other references