A stunning and large example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measure 55 mm (2.15 inches) across and contains a partial ammonite shell. The shell sits in the small original limestone matrix piece in which it was found. The ammonite is very well preserved and has been prepared out of the rock to reveal the shell. The shell displays some beautiful rainbow iridescence with flashes of red, yellow, green, and copper that appear as the viewing angle changes. The colours on this one are fantastic. The matrix is thin making it the ideal drawer specimen.
These fossils are highly sought after and very hard to find, especially complete like this. They are preserved in the same way as the famous Canadian "Ammolite" ammonites that are turned into valuable gemstones. The fossil weighs 10 grams.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.