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.
(Mg,Fe) 5(SiO 4) 2(F,OH) 2Ulrich Henn and Claudio C.