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ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
LiAl(PO 4)(OH,F)Walter Schumann , Gemstones of the world (2001) More from other references
SiO 2 + H 2OUlrich Henn and Claudio C.