Researchers Explore Cahokian Coppersmithing

Artist's rendition of Cahokian settlement.

Researchers have employed 600-year-old metalworking techniques to gain a better understanding of copper artifacts left behind by the Mississippians of the Cahokia Mounds, who lived in western Illinois from 700 until 1400 AD.

The researchers, from Northwestern University, were able to identify how the coppersmiths of Cahokia likely set up their workshop and the methods and tools used to work copper nuggets into sacred jewelry, headdresses, breastplates and other regalia.

"Metals store clues within their structure that can help explain how they were processed," said David Dunand of Northwestern's McCormick School of Engineering and Applied Science and co-author of the paper. "We were lucky enough to analyze small, discarded pieces of copper found on the ground of the excavated 'copper workshop house' in Cahokia and determine how the metal was worked by the Cahokians."

The researchers also tested theories that some archeologists had made about the coppersmiths' techniques. One idea was that they made large copper pieces, like ceremonial breastplates, by "laminating" sheets of copper together through a hammering technique. But the lamination could not be reproduced, even with much greater weights achievable with a modern press.

The other hypothesis ~ that the Cahokians used copper knobs or copper rivets and other mechanical devices to secure sheets of copper together ~ seems more likely.

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