Blue, White, Grey, Yellow, Green, Colorless, Red, gray
Colorless, Yellow, Blue, Reddish, Black, Reddish, Brown, Blue, gray, Black, Reddish, Brown, Blue, gray
Uneven, Conchoidal, Brittle
Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
(Na,Ca)4-8Al6Si6(O,S)24(SO4,Cl)1-2
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references