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