Uneven, Uneven, Gems, Sixth Edition (2006)
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
KAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
CaBe 2(PO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006)