ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, Conchoidal, UnevenArthur Thomas, Brittle
ZrO 2Arthur Thomas , Gemstones (2009)
Fe2+ CO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references