White, Colorless, Blue, Red, Green, Yellow, Violet
Colorless, Blue, Violet, White, Brown, Colorless, Blue, Violet, White, rose, Brown, gray, Colorless, White, Violet, gray, Colorless, White, Violet, gray
Conchoidal, Conchoidal, Gemstones of the world (2001)
Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references