White, Colorless, Blue, Red, Green, Yellow, Violet
Colorless, Yellow, Blue, Reddish, Black, Reddish, Brown, Blue, gray, Black, Reddish, Brown, Blue, gray
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
SiO 2 + H 2OUlrich Henn and Claudio C.
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references