Brown, Colorless, Brown, Brownish, Black, Colorless, Green, Greenish
Colorless, White, Brownish, Reddish, Black, Brownish, Black, Colorless, gray, White, Reddish, Brown
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven
ZrO 2Arthur Thomas , Gemstones (2009)
Na 3AlF 6Ulrich Henn and Claudio C.