Fluorite with Chalcopyrite

specimen number:
2013493

location:
Mahoning #7 Mine, Hardin Co., Illinois, USA

description:
A gorgeous cluster of amber colored glassy gemmy cubic fluorite crystals, these hosting small brassy crystals of chalcopyrite throughout. Some of the chalcopyrite is present as inclusions. This is in excellent condition. Beautiful when backlit as shown in the picture and at the end of the video. There is a thin color zone of purple around the edges to really make this pretty. An excellent old-timer.

The Mahoning Number 7 Mine, situated near Cave-In-Rock in Hardin County, Illinois, was a premier operation within the Illinois-Kentucky Fluorspar District. It was operated by the Mahoning Mining Company (a subsidiary of the Youngstown Sheet and Tube Company) and was active primarily from its opening in the early 1940s through its closure in the late 1950s. Geologically, the mine exploited bedded replacement deposits within the Mississippian-aged Fredonia Limestone member of the Ste. Genevieve Formation. These deposits occurred where fluorine-rich hydrothermal fluids were trapped beneath impermeable shale layers, replacing the limestone with high-grade fluorite. The Mahoning Number 7 is legendary among collectors for producing some of the finest fluorite specimens in the world, characterized by their sharp cubic forms and stunning color zoning in shades of yellow, blue, and purple. After production ceased, the site became part of the broader history of the district's decline as domestic mining was phased out in favor of international sources.

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