Uneven, Uneven, Gemstones of the world (2001) More from other references
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
(Ca,Cr)MgSi 2O 6Gemdat.org , Management Team (2012)