Uneven, Conchoidal, Brittle, Metallic, ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), (e.g. graphite).
Ca 3Cr 2(SiO 4) 3Ulrich Henn and Claudio C.
PbCrO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references