Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Uneven, Conchoidal, Brittle, Metallic, ConchoidalArthur Thomas, Gemstones (2009)
Fe 2O 3Arthur Thomas , Gemstones (2009)
Ca 3Cr 2(SiO 4) 3Ulrich Henn and Claudio C.