Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
SiO 2Michael OâDonoghue , Gems, Sixth Edition (2006)
MgAlBO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references