ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), (e.g. graphite).
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
PbCrO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
ZrO 2Arthur Thomas , Gemstones (2009)