Uneven, Gemstones (2009), Splintery
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Ca 2NaHSi 3O 9Ulrich Henn and Claudio C.
CaBe 2(PO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006)