White, Colorless, Blue, Red, Green, Yellow, Violet, pink
Colorless, Greenish, Colorless, Green, gray, Yellow
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Irregular/uneven, Uneven
(Be,Cs) 3Al 2Si 6O 18 · 0.5H 2OUlrich Henn and Claudio C.
Ca 2Al 3(SiO 4) 3(OH)Walter Schumann , Gemstones of the world (2001) More from other references