Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Ca 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
Mg 2Si 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references