Ammolite is a rare colourful gemstone formed during the fossilisation process of ammonites. Found in the Bearpow formation. Read more.
Rare fossilised gemstone
Ammolite is a rare gemstone that is only found on a limited scale in the Bearpow formation, which runs from the south of Canada to Montana in the USA. What makes ammolite so special is its origin. It is one of the few fossil gemstones in the world. The other two are amber and pearls. Ammolite is a fossilised shell of the 'Placenticeras meeki' and the 'Placenticeras intercalare' ammonite.
The ammonites lived between 75 and 70 million years ago in the Bearpow Sea, which was then located inland of North America. Because of the unique fossilisation process in which very thin plates of aragonite were formed, the light is reflected in beautiful opal-like colours. Green and red are most common, but depending on the thickness of the plates, the entire spectrum of colours can occur.
The iridescent colour of ammolite consists of a very thin layer (+/- 0.5 to 0.8 mm) covering the ammonite. Many ammolites are therefore processed into triplets. The thin layer of ammolite is put on a solid underlayer and the top is covered with a transparent coating. The advantage of this is that the ammolite is protected against damage and with the topping, the play of colours is optimally visible.