Handbook of mineralogy (2001), Difficult, Fibrous
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Ca 6Si 6O 17(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
CaBe 2(PO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006)