Colorless, White, Brownish, Reddish, Black, Brownish, Black, Colorless, gray, White, Reddish, Brown
Colorless, Greenish, Colorless, Green, gray, Yellow
Na 3AlF 6Ulrich Henn and Claudio C.
Ca 2Al 3(SiO 4) 3(OH)Walter Schumann , Gemstones of the world (2001) More from other references