Colorless, Yellow, Blue, Reddish, Black, Reddish, Brown, Blue, gray, Black, Reddish, Brown, Blue, gray
White, Colorless, Blue, Red, Green, Yellow, Violet, pink
Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
(Be,Cs) 3Al 2Si 6O 18 · 0.5H 2OUlrich Henn and Claudio C.