Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Uneven, Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Uneven, Subconchoidal, Brittle, Metallic, Brittle, Metallic
Ca 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
Zn 2(AsO 4)(OH)Michael OâDonoghue , Gems, Sixth edition (2006)