Mirror finished 'Pyrite', commonly known as 'Fools Gold', crystallises in cubic form and has tricked many to believe they had found the elusive golden prize, 'Gold', however, they were fooled. These amazing cubic forms are natural, not engineered by man but by nature.
It's not difficult to analyse the difference between pyrite and gold once the obvious has been made aware.
The La Rioja only produces Iron Pyrites, not for commercial purposes for industry; it is solely a concern producing fine specimens for collectors and enthusiasts. Many specimens from the source reside in the museum across the world.
As seen in the images above and below, iron pyrite has replaced the internal structure of the fossil ammonites shell, chamber walls and cavities, absorb by surrounding mineral deposits over millions of years during the fossilisation process, creating these bizarre and stunning golden structures within the Rondiceras ammonite shellhell. Originating from Mikhailov, Volga river, Ulyanovsk near Saratov, Ryazan region of Russia. They date back to the Mesozoic era, middle Jurassic period, Callovian stage, approximately 164 to 161 million years ago.