Uneven, Brittle, Metallic, Gemstones (2009)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Na 2[Al 2Si 3O 10] · 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Na 2(Ti,Fe)Si 4(O,F) 11Ulrich Henn and Claudio C.