ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
SiO 2Ulrich Henn and Claudio C.
MgAlBO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references