Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Conchoidal, Uneven, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal to uneven
Na 2(Ti,Fe)Si 4(O,F) 11Ulrich Henn and Claudio C.
Ca 5(PO 4) 3(F,OH,Cl)Walter Schumann , Gemstones of the world (2001) More from other references