Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references
3CaAl 2Si 2O 8 · CaCO 3Anthony et al , Handbook of mineralogy (2001)