UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
Fe 2O 3Arthur Thomas , Gemstones (2009)