One of the oldest examples of Indigenous mining documented in North America, a series of small Isle Royale copper mines, has been designated an official National Historic Landmark.

Archaeological and historical evidence suggests copper mining activity by native groups at the Minong copper mine started at least 4,500 years ago and continued into the 1900s.

The National Park Service announced the designation Thursday. Minong is the Ojibwe word for Isle Royale.

The newly designated historic site covers about 200 acres on Lake Superior’s largest island, including multiple small pits where copper was mined and an apparent settlement where Native people lived near the mines at McCargoe Grove.

The site also includes remnants of the Minong Mining Co. , which mined on the island from 1875 to 1885, one of several short-lived copper mining operations on the island at that time.

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Gary Meader / Duluth News Tribune
Gary Meader / Duluth News Tribune

As highlighted in the report nominating the site as a national landmark, authored by professor Daniel Trepal, of Michigan Technological University, the Minong Copper Mining District is nationally significant. The site has high integrity, meaning it hasn’t been disturbed by modern human activity, and combines one of the largest, best-preserved Indigenous copper mining landscapes in the nation.

The site was well used because the copper was so close to the surface, allowing Native people to chisel it out with their simple hand tools, namely rocks taken from the Lake Superior beach.

Isle Royale now is a mostly wilderness national park that sits about 14 miles off Minnesota’s North Shore from Grand Portage.

“Much of our modern archeological knowledge of Indigenous native copper mining methods stems from field research undertaken at this site,’’ the Park Service said in announcing the National Historic Landmark designation.

“This National Historic Landmark designation for the Minong Copper Mining District cements its stature as an exemplary archeological site,” Denise Swanke, Isle Royale superintendent, said in a statement. “Indigenous mining activities figured prominently in the park’s 1931 enabling legislation and the district benefits from being in designated wilderness within a national park, which will help ensure retention of a high level of integrity.”

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When humans first arrived in North America, some 15,000-20,000 years ago, Isle Royale was still covered with thick glacial ice, the Park Service notes. By the time the ice receded from the Lake Superior area and Isle Royale rose above the waters of the lake, about 10,000 years ago, Indigenous people had already begun to occupy parts of the Great Lakes.

The island visitors developed a method of extracting the raw copper from the bedrock by beating it free with rounded, hand-held beach cobbles. Numerous pits were dug in the most productive locations on the island, especially along Minong Ridge. Recent archeological excavations have uncovered large numbers of hammer stones from the ancient mines, which are now filled in by soil and covered with vegetation.

The copper itself was cold-hammered into knives, spear points and a variety of ornaments, either on Isle Royale or taken to the mainland and then worked. Artifacts made from this local copper have been found as far away as New England.

More than 1,000 pits attributed to Indigenous people have been located on Isle Royale. It’s believed they were found not in an intentional search for copper at first, but as people visited the island to hunt, fish and gather food.

National historic landmarks are buildings, sites, districts, structures and objects that have been determined by the secretary of the Interior to be nationally significant in American history and culture. All national historic landmarks are included in the National Register of Historic Places, the official list of the nation's historic properties.

Before resources can be designated as national historic landmarks, they must be evaluated by the National Park Service's National Historic Landmark Survey, reviewed and recommended by the National Park System Advisory Board, and signed by the secretary of the Interior.