Calcite

specimen number:
2013622

location:
Ozark Mahoning #1 Mine, Hardin Co., Illinois, USA

description:

A unique and very attractive grouping of chatoyant calcite crystals without matrix. This is in super condition all around. At one time this was in the collection of Rick Russell of Cincinnati, Ohio.

The Ozark-Mahoning Number 1 Mine, located in the Cave-in-Rock District of Hardin County, Illinois, was a premier producer within the world-famous Illinois-Kentucky Fluorspar District. Geologically, the mine exploited Mississippi Valley-Type (MVT) deposits where hydrothermal fluids replaced specific Mississippian-aged limestone layers, particularly within the Ste. Genevieve and Renault Formations, creating extensive flat-lying "mantos" or bedded replacement ores. These deposits are legendary for producing some of the world's finest fluorite specimens, characterized by their vibrant purple, blue, and yellow cubic crystals, often found in association with sphalerite, galena, and barite. Historically, the Ozark-Mahoning Company began significant development of this specific shaft in the early 1940s to meet the surging industrial demand for fluorspar in steel and aluminum production during World War II. The Number 1 Mine remained a cornerstone of the district's output for decades, operating through the mid-20th century until the gradual decline of the domestic fluorspar industry led to its closure in the late 20th century. Today, the mine is remembered not only for its massive industrial contributions but also as a premier source for the museum-quality fluorite clusters that define the mineralogical heritage of southern Illinois.

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