Where to Find Chalcopyrite in Missouri

Chalcopyrite is the principal copper sulfide in Missouri's Mississippi Valley ores, where it occurs as a minor associate of galena and sphalerite. The Viburnum Trend mines (Sweetwater, Buick, Brushy Creek) produce tetrahedral chalcopyrite up to two centimeters on dolomite matrix, often with iridescent tarnish films. The Old Lead Belt around Bonne Terre yields smaller chalcopyrite grains in massive galena ore. Mine La Motte in Madison County adds chalcopyrite alongside its copper-cobalt-nickel ores. Surface specimens tarnish quickly to peacock colors; freshly fractured crystals are bright brassy yellow and a fingernail-scratch test distinguishes from pyrite. The most productive ground is in Sweetwater mine (Reynolds County), Brushy Creek mine (Iron County), Mine La Motte (Madison County).

Casual hand collection of common rocks and minerals like chalcopyrite is allowed on most BLM and U.S. Forest Service land in Missouri, with daily and annual limits set by the local field office. National parks, most state parks, and tribal land are off-limits. Always confirm rules before a trip.

Sweetwater mine (Reynolds County) is the standout. Other strong ground includes Brushy Creek mine (Iron County), Mine La Motte (Madison County).