Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Uneven, Conchoidal, UnevenArthur Thomas, Brittle
Na 3(Na,K)Al 4Si 4O 16Ulrich Henn and Claudio C.
Fe2+ CO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references