"Mineral experts originally theorized that Pyrite Suns were fossilized sand dollars or even ancient lily pads that had been replaced by pyrite. More recently though, mineralogists have speculated that they're actually pyrite concretions which, because they formed between layers of slate, simply had no room to grow into the cubical formations one would normally expect to find. The Pyrite Sun in Slate as seen here is approximately 3" in diameter, although each piece will vary slightly as determined by nature. It was formed 350 million years ago in a thin seam of slate above a coal deposit in what is now Southern Illinois. A wonderful gift for kids and adults alike! Also makes a unique decorator item for the home or office. As featured in Miss Congeniality 2."