Composition
Fossilized shells of the extinct marine ammonite species Placenticeras meeki, Placenticeras intercalare, or less commonly Baculites compressus may have an inner layer made of ammolite. The shells, including the ammolite layer, are made of the mineral aragonite, a form of calcium carbonate. Not all ammonite shells have ammolite.
Age and Formation
Ammonite fossils are found in ancient ocean floor sediments of the Bearpaw Shale (72 - 75 million years ago). Why ammolite is found in some shells in a few locations, but not all, remains a mystery. It’s possible that ammolite only forms under unique pressure and chemical conditions at the time of fossil preservation.
Important properties
Ammolite is a gemstone prized for its rainbow-coloured play of light. Although brittle, it can be stabilized with resins, mounted on a medium, and capped to preserve its brilliant colours. Alberta is the only place in the world where ammolite is mined commercially.
Uses
Ammolite is primarily used to make jewelry. Whole and partial ammonites bearing ammolite are sold as collectibles and decorations. It has been documented that portions of ammonite shells are used by Indigenous Peoples as iniskim (buffalo calling stones) to assist in hunting rituals, and as medicine objects.
It’s a Fact!
Ammolite is used in the practice of feng shui.
Discover!
Billy Jack, Indigenous Ammolite Prospector
Comprehensive article on ammolite from “Gems & Gemmology”
Where to find ammolite
