UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)