ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
ZrO 2Arthur Thomas , Gemstones (2009)
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)