ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), (e.g. graphite).
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
PbCrO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
CaBe 2(PO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006)