A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 110 mm (4.4 inches) wide and the ammonite measures 78 mm, which is a good size for this species. The shell sits in the original limestone matrix in which it was found that has been shaped for display. The ammonite is very well preserved and has been prepared out of the rock to reveal the whole shell. The shell displays stunning iridescence, showing all of the colours of the rainbow that change as the angle of light changes, with green and orange colours dominating. There is also a smaller ammonite shell with green iridescence next to the main ammonite. It has a cut-flat base and plaster wedge on the back to allow it to stand freely for display purposes.
These fossils are highly sought after and very hard to find. They are preserved in the same way as the famous Canadian "Ammolite" ammonites that are turned into valuable gemstones. The fossil weighs 150 grams.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.