Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
PbCu(SO 4)(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
Ca 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)