Uneven, Brittle, Metallic, Gemstones (2009)
Subconchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
Na 2[Al 2Si 3O 10] · 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Ca,Ce)(Al,Ti,Mg)12O19