Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)
SiO 2 + H 2OUlrich Henn and Claudio C.