Colorless, Greenish, Colorless, Green, gray, Yellow
Brown, Yellow, White, Brown, Greenish, Yellow, White
Irregular/uneven, Uneven
Uneven, Even, Yellow, White
Ca 2Al 3(SiO 4) 3(OH)Walter Schumann , Gemstones of the world (2001) More from other references
K(Mg,Fe++)3[AlSi3O10(OH,F)2