ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
CaTiSiO 5Ulrich Henn and Claudio C.
(Ca,Cr)MgSi 2O 6Gemdat.org , Management Team (2012)