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