ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Be 3Al 2Si 6O 18Ulrich Henn and Claudio C.
(Ca,Cr)MgSi 2O 6Gemdat.org , Management Team (2012)