Uneven, Uneven, Gems, Sixth Edition (2006), Uneven, Conchoidal
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
NaAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
ZrO 2Arthur Thomas , Gemstones (2009)