ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Conchoidal, Metallic, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
ZrO 2Arthur Thomas , Gemstones (2009)
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references