Blue
Colorless, Colorless, Violet, White
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Be 3Al 2Si 6O 18Ulrich Henn and Claudio C.
Ca 3Al 2(SO 4)(F,OH) 10Ulrich Henn and Claudio C.