UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references