Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Fe 2O 3Arthur Thomas , Gemstones (2009)
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)