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