ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001), Brittle, Metallic
Uneven, Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Uneven, Subconchoidal, Brittle, Metallic, Brittle, Metallic
BeAlSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Zn 2(AsO 4)(OH)Michael OâDonoghue , Gems, Sixth edition (2006)