Interestingly, some of the most fascinating evidence of prehistoric mining is found in North America. On the Kewinaw Peninsula and on Royal Island in Michigan, in the copper-rich region of Lake Superior, there are ancient mines whose origins are completely unknown even to the Indians. There are indications that several thousand tons of copper were mined at a very early time, and there is not a single cultural attribute that could tell us who these miners were.
An American Antiquary (Chapter 25, p. 258) notes, “There is no sign of any permanent settlement near these mines. No remnants of housing, skeletons, or bones have ever been found. What is known is that prehistoric miners had the means not only to extract the ore, but also to transport it to some distant location, and not one ounce of ore was ever excavated for use within a thousand miles of mining sites.
On Royal Island, near the northern shore of Lake Superior, prehistoric mining is very extensive, with several mine passages reaching 60 feet. After the discovery of one of the island mines, prospectors discovered that the mine had been dug nine feet deep through solid rock before an 18-inch thick copper vein was exposed at the bottom. Obviously, the miners were very intelligent and experienced and conducted research and observation of the location of copper veins, and then in the following rocky underground, down to the surface. The Royal Island mines extend for up to two miles in an almost straight line.