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