"Float" copper is found throughout the "Copper Country" of Michigan and many nearby states. Glacial movements thousands of years ago altered the geologic deposits of the native copper by tearing and scouring the land. Copper, along with other rocks, gravel, and sand were constantly tumbled and deposited over large areas of the Upper Midwestern United States.
Exposure to the soils, water, and air has oxidized the copper surface a bright green. These specimens with the natural oxidation color provide a good contrast to the polished copper surface of the cross-sections.