Pyrite suns are found 300 feet deep in the coal mines of Randolph County, Illinois in a narrow seam of shale lying on top of the coal vein. They date back 310-350 million years.
One of the formation theories is that the suns formed in flat radial patterns because they formed between bedded materials. The crystals did not have room to form in the cubic system but rather developed raially.
Scanned by Artur Pacyga in Dr. Franek Hasiuk's GeoFabLab (Department of Geological and Atmospheric Sciences, Iowa State University).
Scanned with the MakerBot Digitizer Desktop 3D Scanner set on "Medium"