Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references