Conchoidal, Metallic, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
SiCArthur Thomas , Gemstones (2009)