Uneven, Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Uneven, Subconchoidal, Brittle, Metallic, Brittle, Metallic
Splintery, UnevenArthur Thomas, Difficult, Fibrous
Zn 2(AsO 4)(OH)Michael OâDonoghue , Gems, Sixth edition (2006)
NaAlSi 2O 6Ulrich Henn and Claudio C.