Splintery, UnevenArthur Thomas, Difficult, Fibrous
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
NaAlSi 2O 6Ulrich Henn and Claudio C.
CaBe 2(PO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006)