Buy this Rock n Gem Magazine issue with the ammolite article complete with stunning pictures,
One of the newest gemstones to appear recently on to the global market is Ammolite. Here in the United Kingdom, very few people have heard let alone seen this beautiful gemstone. Often Ammolite and Ammonites are confused but in fact are interrelated.
In our attempt to understand the gemstone Ammolite and its origins, we know that Ammonites are found all over the world, also here in the UK where the area of Lyme Regis and Charmouth are identified as areas where one can find specimens especially after a storm and where the cliffs have eroded. These are typically preserved shells of an ancient species of invertebrate animal that once dominated the earth's seas.
When North America first appeared as the Pacific Plate thrust up from below - forming Earth's newest cordillera, the Rocky Mountains - the Bearpaw Sea ran up the middle. It extended from what is presently the Arctic Circle to the Gulf of Mexico. It was warm, sheltered and teeming with life. In the shallows along the eastern slope of the Rockies there was an abundance of animals hunting,
feeding, breeding and dying. It held familiar creatures like Crabs, Lobsters, Cuttlefish, Turtles, Sharks and Ammonites swimming alongside prehistoric beasts such as Mosasaur, Ichthyosaurs and ten ton fish with jaws like draglines and teeth in the hundreds. They were thriving in an ocean that was rich with plankton due to the enormous amount of fresh water that flowed into it from the Rockies. This
is also when the dinosaurs made their brief appearance on the lands.
The Ammonite was among the most successful of species in this late Cretaceous marine tableau. It evolved from a common ancestor into a genus over fifty thousand species strong. They filled every
ecological niche in the early oceans. Some were passive plankton feeders that relied on the currents for movement. Other species were aggressive predators that hunted in packs, jetting along via hydro propulsion with powerful, razor-sharp beaks.
These creatures had one of the largest brains of their time and the largest specimen on record (found on the Antarctic continent) was over ten meters long. Ammonites thrived in every ocean on the planet.
Populations rose and fell, diversified into new forms then suffered periodic extinctions, only to mysteriously proliferate again. They continually evolved and adapted to changing climates and ecospheres.
In Ammonite structures, tubercles are found on the exterior of the shell which are bony protuberances (like small horns) along two converging lines of the spiral of the male. In the species Placenticeras
Intercalare this is also referred to as a "nipplite" and in Ammolites produces a spectacular rainbow eye that dances and follows the light.
Striations are natural wave like ribs that provided structural strength to the shell of the Ammonite and in Ammolites give rainbow lines that flow across the gemstone.
A Siphuncle was a tube structure that ran inside the edge of the spiral shell and controlled the buoyancy of the creature. Hand polished Ammolite gems from this portion of the fossil have gem material covering around three sides of the stone.
Suture gems show a distinctive leaf pattern in shallow indentations of the surface and occur through the partial collapse of the shell surface as it conforms around the fractal structure of the shell wall.
The Ammonite Placenticeras had the most complex suture lines of any of its kind. From a straight line on the vertical axis dividing the chambers of the animal like a wall it becomes infinitely broad as well
as long and becomes the shell covering itself.
Researchers today are divided on whether or not Mosasaurs and other marine reptiles ate Ammonites.
Some believe that the circular marks found on Ammonite fossils were made by Limpid Eels, a barnacle like parasite that would attach itself to the shell of the Ammonite and, with the help of gastric acids, bore in for a meal.
Cataclysmic volcanic activity from the growing Rocky Mountains periodically covered huge areas with meters thick ash that settled slowly to the shallow ocean floor killing all life below and capping the
remains beneath an iron rich Bentonite Clay. The clay effectively sealed off this layer of marine deposition and created a unique environment for mineralization. This is one of the theories behind the
development of the brilliant colours of the Bearpaw Ammolites.
