Copper and Iron, The Upper Peninsula's Mineral Age

In the summer of eighteen forty-one, a federal geologist named Douglass Houghton filed a report with the state of Michigan describing copper deposits in the Keweenaw Peninsula so abundant that they strained credibility. He wrote of copper boulders lying on the surface of the ground, of veins running through ancient rock that geologists now know are one point one billion years old. The report touched off a copper rush that transformed an obscure peninsula on the southern shore of Lake Superior into one of the most industrially productive regions in North America.

The Keweenaw's copper was unusual. Unlike most copper ore, which requires smelting to extract metal from rock, much of the Keweenaw deposit was native copper, metallic copper in pure form, embedded in basalt. Indigenous people had worked it for thousands of years.

The Old Copper Culture, as archaeologists call it, was working Keweenaw copper into tools and ornaments as early as five thousand years ago, making it one of the oldest metalworking traditions in the Western Hemisphere. The American copper rush of the eighteen forties brought a different scale of extraction. By the eighteen seventies, the Keweenaw was producing three-quarters of the copper mined in the entire United States.

The company town of Calumet and the surrounding mining district employed tens of thousands of workers, Cornish miners, Finnish immigrants, Italians, Slovenians, living in company housing, shopping at company stores. Iron ore followed a similar arc. The Marquette Iron Range, discovered in eighteen forty-four, and the Menominee and Gogebic ranges that followed, produced iron ore that fed the furnaces of Pittsburgh and Cleveland for a century.

Michigan was the nation's leading iron ore producer for most of the second half of the eighteen hundreds. Both industries eventually declined. The copper mines closed through the nineteen sixties, the last major iron mines in the nineteen nineties.

The landscape they left behind is extraordinary, cavernous headframes, machine houses built like medieval fortresses, shafts that descend a mile and a half into the earth. Keweenaw National Historical Park now preserves the industrial ruins of the copper country.