Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
SiO 2Ulrich Henn and Claudio C.