Have you ever heard of ammolite? It is an opal-like gemstone made from the iridescent shells of ammonites. These beautiful examples are from the Korite Mine, just outside of Lethbridge, Alberta, Canada. All these specimens derive from specific horizons of the Late Cretaceous Bearpaw Formation (not where you find bear paws!). They are roughly 71 million years old. | Dr Dean Lomax - Palaeontologist

Still my favorite Ammolite. I found this in the Pierre shale formation. Loads of public land in the area to prospect. | That Camping Couple