A stunning and large example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 165 mm (6.5 inches) across and contains an ammonite that measures 93 mm (3.68 inches), which is a good size for this species. The ammonite sits in the original limestone matrix in which it was found that has been shaped and has a cut-flat base with plaster wedge on the back to allow it to be displayed freely standing.
The ammonite is very well preserved and has been prepared out of the rock to reveal the shell, which displays some beautiful iridescence that causes the colours to change as the viewing angle changes. Deep orange, green, and red tones dominate the shell colour. The fossil weighs 252 grams.
These fossils are highly sought after and hard to find, especially large complete examples like this one. They are preserved in the same way as the famous Canadian "Ammolite" ammonites that are turned into valuable gemstones. These fossils make great unusual gifts and each one is totally unique. Large examples like this are rare and hard to find.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.