Fluorite with Hematite, Chalcopyrite

specimen number:
2013500

location:
Pea Ridge Mine, Washington Co., Missouri, USA

description:
A wonderful miniature example for the species from this famous locality. The specimen consists of gemmy deep purple cubic crystals of fluorite measuring to 1.9 cm on edge across the top of a hematite matrix. The fluorite crystals are partially coated with microscopic hematite typical of this locality. Crystals of golden chalcopyrite are scattered throughout. In excellent condition.

The Pea Ridge Mine, located in Washington County, Missouri, was one of the largest underground iron ore operations in the United States. Discovery of the massive magnetite deposit occurred in 1947 via airborne magnetometer surveys, leading to the formation of the Meramec Mining Company. Construction of the shafts began in 1957, and the first iron ore pellets were produced in 1964. Geologically, the mine is unique as it exploits a Proterozoic-aged, volcanic-hosted magnetite-apatite deposit located approximately 2,000 feet below the surface. The ore body is a massive, steeply dipping pipe-like structure hosted within rhyolitic tuffs and flows of the St. Francois Mountains volcanic terrane. In addition to iron, the site contains significant concentrations of rare earth elements (REE) within apatite and breccia zones. Most iron production ceased in 2001, though the site has seen intermittent interest for its rare earth potential and specialized iron products in the years since. It remains a classic example of a Kiruna-type iron oxide-apatite (IOA) deposit.

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