Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Na 3(Na,K)Al 4Si 4O 16Ulrich Henn and Claudio C.
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)