Michigan Native Float Copper, Keweenaw Peninsula
14" x 5" x 11" / 18 lbs
"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. The long period of burial, ca. 9000 years, since the cessation of glacial action, oxidized the surface copper. The resulting oxidation products are primarily malachite (green copper carbonate) and cuprite (red copper oxide). This rare specimen was folded (and subsequently unfolded) by glacial movements some 10,000 years ago.