Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
Fe 2O 3Arthur Thomas , Gemstones (2009)
Mg 3(SiO 4)(F,OH) 2Anthony et al , Handbook of Mineralogy (2001)