ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
[C,H,O]
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)