The Legend of Copper Mounds
What can copper mounds tell us about the history of metallurgy?
Some of our columns contain more metallurgy than others. Some contain well-known history. This month’s nonferrous-focus drew us to the history and legend of the “copper mounds” of North America. Michigan is particularly replete with these mounds. A 1925 archaeological book indicated, “There are fully 600 mounds still to be seen in the state and at least 500 more must have been destroyed in the last 150 years.”
Who made these mounds, and why were they made? Unfortunately, some of this information is prehistoric, but history, legend and archaeology reveal some of the mystery. Some archaeologists believe that the mound builders were intelligent, had entered the Bronze Age and traded with the Aztecs and Mayans. Dr. Henriette Mertz, in her 1985 book The Mystic Symbol, believes that ancient Phoenician mariners traveled across the ocean to Upper Michigan to mine the pure and abundant lodes to satisfy the demands of ancient Egyptians and Greeks. Records indicate that it took three years for the ocean vessels to return with their copper.
While Michigan copper is documented throughout the New World, archaeologists have also found it in artifacts around the world. Scientists agree that they date back thousands of years before Christ. Keep in mind that access to this area could be gained through the St. Lawrence Seaway. Around the north shore of Lake Superior and on the adjacent Isle Royale, there are approximately 5,000 ancient copper-mine workings. Carbon dating of objects found in the area indicates that the mines must have operated between 2000 B.C. and 1000 B.C.
But why would mariners travel so far for copper? There are likely several reasons. One is clearly that demand was drying up European sources. Another reason was that the copper available here needed no refining. It is the only known source of pure raw copper. One Michigan copper mine yielded a 6,000-pound copper boulder that was later seized by the U.S. Secretary of War for the Smithsonian Institution.
One of the reasons Old World sources were drying up is mentioned in the Bible. It indicates that ancient Israel, under King David, was stockpiling massive quantities of copper and copper ore around 1000 B.C. There is evidence that David’s allies, the Canaanite Phoenicians, were involved in the New World copper trade and that some of David’s huge stockpile came from North America. It is believed that the North American mines were depleted during the reign of Solomon.
The fate of the mound builders is not really known, but William Pidgeon’s 1858 book Tradition of De-Coo-Dah states that De-Coo-Dah described an ancient race of mound-building people – likely the copper miners – who were much more numerous than the Indians. A news article from 1956 describes a conversation with an elderly Indian who refused to take an archaeologist to an ancient mound site because of the ghosts of Yam-Ko-Desh – Ottawa for “the prairie people.” Ottawa legend tells of finding the prairie people who were “thicker than the leaves on a tree.” It is believed that the Ottawas, Ojibwas and Potawatamis formed an alliance to wipe out the prairie people.
When copper is found in less-pure sources, it needs to be extracted from the ore. Three different minerals contain copper – cuprite, malachite and azurite. Copper is extracted from these ores by smelting. Early smelting occurred in a hole 1 to 2 feet in diameter that was lined with fire-resistant clay or stone. Charcoal was placed in a layer on top of the clay, which was then covered by copper ore. This early open-hearth furnace produced molten copper as the hot-burning charcoal generated enough heat, and the reducing nature of the gases contributed to the reaction. The basic chemical reaction is as follows:
2CuO + C → 2Cu + CO2
As early as 3500 B.C., at the modern site of Cairo, an entire civilization developed based on the metallurgy of copper. This group learned basic copper metallurgy (as described in the previous paragraph) from Mesopotamian immigrants.
Early copper workers also discovered that heating – annealing – made copper more malleable. Interestingly, the early documented inhabitants of the Michigan mound area – the Ojibwa, for one – rarely used copper for weapons because of the mystical beliefs they associated with the metal. While archaeological digs have unearthed some copper spears and arrow points, more often items such as wristlets, necklaces, rings and beads were found. Hammered dishes and bowls are also among the discoveries.
Now you know more about how metals and their production have established and even eliminated groups of people throughout time. IH