ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
CaZrBAl 9O 18Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.