Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Splintery, Conchoidal, Uneven, Splintery, Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001)
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references
SiO 2Arthur Thomas , Gemstones (2009)