Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Gems, Sixth Edition (2006)
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Quartz: SiO2 Rutile: TiO2