ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
UnevenWalter Schumann, Gemstones of the world (2001) More from other references, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Uneven
SiO 2 + H 2OUlrich Henn and Claudio C.
(Zn,Fe)SMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references