ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
MnTa 2O 6Walter Schumann , Gemstones of the world (2001) More from other references
(Ca,Cr)MgSi 2O 6Gemdat.org , Management Team (2012)