Eternal Brilliance

The 71-Million-Year Journey of Ancient Ammonites

- BY AMARJEET GREWAL

Not all treasures stay buried; some endure. More than 71 million years ago, beneath the waves of a vast inland sea, spiral-shelled ammonites thrived along what is now southern Alberta, Canada. Over time, their shells—layered in delicate aragonite—were preserved and transformed, capturing the full spectrum of light. Today, this transformation is known as Ammolite: a rare and radiant gemstone, alive with shifting color, carrying the legacy of the ancient sea in every iridescent layer.

In the fossil-rich beds of southern Alberta, something uncanny glimmers beneath the surface. Ammolite refuses to fade. Polished and preserved, these ancient remains shimmer in electric greens, fiery reds, deep blues and ultraviolet purples-as if channeling a ghostly memory from a lost world."

In the fossil-rich beds of southern Alberta, something uncanny glimmers beneath the surface. Ammolite refuses to fade. Polished and preserved, these ancient remains shimmer in electric greens, fiery reds, deep blues and ultraviolet purples—as if channeling a ghostly memory from a lost world.

This isn’t your typical fossil. Ammolite is a mineralized resurrection. And in a world fascinated by the supernatural, each October, it just might be the closest thing geology gets to the undead.

RESURRECTED BY ROCK: THE SCIENCE BEHIND THE SPECTACLE

While most fossils are shades of stone—greys, blacks and browns—Ammolite stands apart. It owes its spectral glow to aragonite, a crystal form of calcium carbonate. In rare cases, the aragonite layers in an ammonite shell remain intact during fossilization. These wafer-thin layers bend light through interference, much like opal or butterfly wings.

What you're seeing is an ancient structure, not pigment. The colors are an optical illusion caused by the way light refracts through microstructures in the fossil shell: nature's hologram.