Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
PbCu(SO 4)(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
SiCArthur Thomas , Gemstones (2009)