ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, UnevenArthur Thomas, Gemstones (2009)
Na 2Ca 2(CO 3) 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
KCa 4Si 8O 20(F,OH) · 8H 2OUlrich Henn and Claudio C.