Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Fe 2O 3Arthur Thomas , Gemstones (2009)
Ca 5(PO 4) 3FAnthony et al , Handbook of mineralogy (2001)