Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, UnevenArthur Thomas, Gemstones (2009), Splintery
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
Ca 2(Mg,Fe) 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.