An Opalised Ammonite, Sphenodiscus lenticularissp. South Dakota, United States of America, Upper Cretaceous period (approximately 65 million years old). Estimate £12,000 – 18,000 (€15,000 – 23,000). Photo Bonhams.
On a perspex display stand. 10.8ins.(27.5cm)wide.
Notes: This exceptional ammonite specimen displays an intense red opal-like iridescence colour on both sides; fused with occasional flashes of green and golden yellow.
During the fossilisation process, the natural nacreous shelllayer was transformed chemically, resulting in a play of vivid colour.
Bonhams. GENTLEMAN’S LIBRARY SALE. 27 Jan 2015 11:00 GMT – LONDON, KNIGHTSBRIDGE