Pyrite

specimen number:
9892102

location:
Marissa Mine, Randolph Co., Illinois, USA

description:
A brilliant golden lustrous disc of crystallized pyrite. In super condition. These are often referred to as pyrite suns.

Sparta, located in Randolph County, Illinois, was founded and settled around 1812 and officially incorporated in 1837. The city sits within the Illinois Coal Basin atop Pennsylvanian-age sedimentary strata of the Carbondale Formation, which features rich coal seams and marine shales formed roughly 300 to 315 million years ago. While Sparta itself is an active modern municipality rather than a closed ghost town, its historic underground and surface coal mining operations peaked during the 19th and 20th centuries before largely winding down due to shifts in energy markets and environmental regulations.

People often refer to "pyrite suns" (also called miner's dollars) as rare, flat, disk-like mineral concretions composed of iron sulfide that feature brilliant metallic crystals radiating outward from a central point like the rays of the sun. Formed under immense vertical pressure within the organic shales directly adjacent to coal seams near Sparta, these formations were forced to grow laterally in thin layers rather than forming standard cubic crystals.

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