Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Ca 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references