#ammolite

Deep Sea December 2025: Day 6-Crystal

The shells and hard structures built by many oceanic organisms are made up of calcite and aragonite crystals! Modern mollusks, oysters, and corals are all examples of this. Extinct species, like this ammonite also used these crystal structures, occasionally during the fossilization process ammonite shells can form a crystal called ammolite. As can be seen in the pictures below ammolite has a very pretty rainbowy iridescence, that was incredibly fun to paint!!

@montereybayaquarium

Behold the dazzling colors of an iridescent ammonite (Placenticeras intercalare)! A relative of today’s squids, this ammonite lived some 80 million years ago near what is now Alberta, Canada. This fossil’s spectacular coloration is the result of millions of years of high temperatures and pressures. As these forces acted on nacre in this ammonite’s shell, it was transformed into a gemstone known as an ammolite. Along with amber and pearl, ammolite is one of only a handful of gems made by living organisms. You can spot this rare specimen in the Louis V. Gerstner, Jr. Collections Core in the Museum’s Richard Gilder Center for Science, Education, and Innovation!

Giant Natural Ammolite (opalized ammonite shell) from Alberta, Canada. With the rare purple and blue colors.

Ammolite

On another note, Here’s some unseen gems I’ve done occasionally!

The last 3 are Rhodochrosite, Sphalerite and mercury!