Ammolite is an organic gemstone formed from the fossilized aragonite shells of ammonites from the Bearpaw Formation of Alberta, Canada. Its iridescent colors are produced by light diffracting through the microscopic layers of the original shell - the same phenomenon as opal or peacock feathers.

Is this a real fossil or a gemstone?

It is both. Ammolite is a genuine fossilized ammonite shell that has also been classified as an organic gemstone due to its extraordinary iridescent properties. It is not a cast, treatment, or synthetic material.

Why does the color change with the viewing angle?

The color in ammolite is structural, not pigment-based. Microscopic layers in the fossilized aragonite diffract light at different wavelengths depending on the angle of observation - the same physics that makes a soap bubble or peacock feather appear to shift color.

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Rainbow Fossil Ammolite - Authentic Gem-Quality Ammonite Fragment

SKU:80-112-0070-201-36

$59.00 USD

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Dominant Color Multicolor Red Orange Green Blue

Ammolite is one of the rarest and most spectacular gemstones on Earth - an organic gem formed from the fossilized shells of ammonites found almost exclusively in the Bearpaw Formation of Alberta, Canada. The iridescent play of color in ammolite is produced by the same mechanism as an opal or a peacock feather: not pigment, but the diffraction of light through the microscopic structure of the original aragonite shell layers. This authentic Rainbow Fossil Ammolite in the multicolor variant displays the full spectrum - the most varied and visually complex of the five color selections.

An Ancient Shell That Became a Gemstone

The ammonites that became ammolite lived in the Western Interior Seaway approximately 71 million years ago and were buried rapidly in fine sediment that preserved the original aragonite layer of the shell - the same material responsible for the nacre of pearls. Over millions of years, that aragonite was compressed and mineralized while retaining its layered microstructure, producing the gem-quality iridescence that makes ammolite one of the most sought-after organic gemstones in the world. This real gem-quality Cretaceous cephalopod fossil is presented in a glass-topped riker display case with an informational card also serving as the certificate of authenticity.

The Authentic Rainbow Ammolite Fossil - Multicolor

Note: ALL ammolite specimens will exhibit multiple colors depending on the angle of the light. The color choices reflect the dominant color of each piece. This is not a cast. This is a genuine fossil gemstone. Each specimen includes a Mini Museum certificate of authenticity and informational display card. Explore more in our Natural History Collection.