Ammolite is a variety of Ammonites. Ammolite from Alberta, Canada, is considered a gemstone. Ammolite is made of the fossilized shells of Ammonites, which in turn are composed primarily of Aragonite or Calcite. Opalescent shell fragments from other localities are usually called Lumachelle. It is also called gem Ammonite, Calcentine, and Korite. Ammolite is famous for its remarkably vivid play of color, caused by Lamellar structure of the glass-like shell.