Ammonite var. Ammolite (Upper Cretaceous)

Item Description

Striking exotic suture patterns and gorgeous areas of iridescent neon-red, neon-green and peacock-blue ammolite on this beautifully preserved and prepared fossil ammonite from the Upper Cretaceous (100.5 to 66 MYA) of South Dakota. Ammolite is an opal-like organic gemstone found in North America made of the fossilized shells of ammonites and are composed primarily of aragonite. The iridescence is due to the microstructure of the aragonite that comes from interference with the light that rebounds from the stacked layers of the thin platelets that make up the aragonite (Wikipedia). A very fine and complete South Dakota ammonite.