Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Al 2SiO 5Arthur Thomas , Gemstones (2009)
Mg 2Si 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references