Fluorite with Chalcopyrite, Hematite

specimen number:
9892084

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

description:
Outstanding miniature for the species and locality, sharp cubic crystals of fluorite to 2.3 cm on edge, these set on matrix and coated with microscopic hematite. Large golden crystals of chalcopyrite are scattered throughout. Micro-cleaving present on the backside of the piece, this is in good condition. The specimen would have been collected in the 1970s.

The Pea Ridge Mine, located in Washington County, Missouri, began its modern history in 1948 when an airborne magnetic anomaly led to its discovery by the St. Joseph Lead Company. Underground development and shaft sinking followed in the 1950s, with commercial iron ore production officially starting in 1964 through a joint venture with Bethlehem Steel. The mine operated primarily as an underground magnetite producer until its closure in 2001. Geologically, the deposit is hosted within Mesoproterozoic felsic volcanic rocks of the St. Francois terrane, situated inside a collapsed Precambrian caldera. The massive, vertical magnetite orebody is associated with extensive potassium metasomatism, hydrothermal breccias, and unique late-stage breccia pipes that are enriched in rare earth elements, heavy metals, and silica.

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