White, Colorless, Blue, Red, Green, Yellow, Violet
White, Blue, Yellow, Brown, Green, Brownish, Greenish, gray
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Gemstones (2009), Flexible Flexible fragments.
SiO 2 + H 2OUlrich Henn and Claudio C.
Al 2Si 4O 10(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references