UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references