Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Uneven, Uneven, Gems, Sixth Edition (2006), Uneven, Conchoidal
Na 2(Ti,Fe)Si 4(O,F) 11Ulrich Henn and Claudio C.
NaAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)