Red, Blue, Green, Brown, Black
Colorless, White, Brownish, Reddish, Black, Brownish, Black, Colorless, gray, White, Reddish, Brown
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
Uneven
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references
Na 3AlF 6Ulrich Henn and Claudio C.