Chalcopyrite with Hematite, Calcite

specimen number:
9892093

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

description:
Gorgeous iridescent blue crystals of chalcopyrite to 0.5 cm in size across a scalenohedral calcite crystal matrix. Minimal damage is present as seen, this still very good for this 1970s vintage specimen. The calcite crystals are slightly pinkish red in color due to the presence of hematite.

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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