Uneven, Conchoidal, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
FeS 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
ZrO 2Arthur Thomas , Gemstones (2009)