Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
Uneven, Uneven, Gemstones of the world (2001) More from other references
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references