Not Available
Colorless, Blue, Violet, White, Brown, Colorless, Blue, Violet, White, rose, Brown, gray, Colorless, White, Violet, gray, Colorless, White, Violet, gray
Not Available
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