Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, UnevenArthur Thomas, Gemstones (2009)
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
Mg 3Si 4O 10(OH) 2Ulrich Henn and Claudio C.