Brittle, Metallic, Brittle, Metallic
Uneven, Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Uneven, Subconchoidal, Brittle, Metallic, Brittle, Metallic
Be 4Si 2O 7(OH) 2Anthony et al , Handbook of mineralogy (2001)
Zn 2(AsO 4)(OH)Michael OâDonoghue , Gems, Sixth edition (2006)