ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
CaTiSiO 5Ulrich Henn and Claudio C.
SiO 2Walter Schumann , Gemstones of the world (2001)