White, Colorless, Blue, Red, Green, Yellow, Violet
Yellow, Brownish, Reddish, Green, Brownish, Yellow, Green, Yellow, Red
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven
SiO 2 + H 2OUlrich Henn and Claudio C.
(Fe+++,Al)25(PO4)17O6(OH)12•75(H2O)