Green, Greenish, Blue, Red
White, Colorless, Blue, Red, Green, Yellow, Violet
Not Available
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
SiO 2Arthur Thomas , Gemstones (2009)
SiO 2 + H 2OUlrich Henn and Claudio C.