Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
Irregular/uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)
Na 2Ca 2Al 6Si 6O 24(CO 3) 2Walter Schumann , Gemstones of the world (2001) More from other references