Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Mg 3(SiO 4)(F,OH) 2Anthony et al , Handbook of Mineralogy (2001)
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references