A stunning example of an iridescent calcite ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The piece of limestone matrix measures 121 mm (4.75 inches) tall and contains a single ammonite that measures 92 mm across, which is large for this species. The ammonite is well preserved and has been prepared out of the rock to reveal the whole shell. The shell displays some nice pale colouration with a silver sheen and some subtle blue iridescence in patches. A natural fracture from a geological fault runs through the ammonite, adding to the interest in this piece. The fossil weighs 365 grams and has a cut flat base and plaster backing to allow it to stand freely for display.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.