Uneven, UnevenArthur Thomas, Gemstones (2009)
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
KCa 4Si 8O 20(F,OH) · 8H 2OUlrich Henn and Claudio C.
SiO 2(+Al 2O 3)Walter Schumann , Gemstones of the world (2001)