ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
SiO 2 + H 2OUlrich Henn and Claudio C.
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references