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