Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Na 2(Ti,Fe)Si 4(O,F) 11Ulrich Henn and Claudio C.
Be 2BO 3(OH)Ulrich Henn and Claudio C.