a mass of native copper weighing 9,392 lbs. found in 1970, buried under three ft. of soil, (glacial till), about 4½ miles southwest of Calumet. Float copper such as this, was torn loose from fissures and lodes by glacial action and together with other rock materials, carried by the ice sheet for great distances before being deposited as glacial debris, or till. The churning, grinding action at the base of the glacier rounded and smoothed the mass of copper, resulting in the lobate form here. The long period of burial, (about 9,000 years), since the cessation of glacial action, accounts for the thorough oxidation of the surface of the copper. The resulting oxidation products are primarily malachite, (green copper carbonate, CuCo3 Cu (OH)2) and cuprite, (red copper oxide,-Cu2O).
Similar pieces such as this, were often discoverd in Keweenaw and on Isle Royale.
Comments 0 comments