Brittle, Metallic, Brittle, Metallic
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Ca(Mg,Al)3(Al3Si)O10(OH)2
CaBe 2(PO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006)