Copper mining in Michigan

The beginning of copper mining in Michigan, a state of the United States, marked the start of copper mining as a major industry in the United States.

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Native American mining

Native Americans mined copper from small pits on the Keweenaw Peninsula of northern Michigan as early as 3000 B.C. By the time the first white men arrived, the area was the home of the Chippewa people, who did not mine copper. The first written account of copper in Michigan was given by French missionary Claude Allouez in 1667. He noted that Indians of the Lake Superior region prized copper nuggets that they found there.^[1] When American prospectors arrived in the 1840s, the copper pits abandoned by Native Americans led them to most of the early successful mines.

Geology

The Copper Country is highly unusual among copper-mining districts in that the copper is predominantly in the form of copper metal (native copper) rather than the copper oxides or copper sulfides that form the copper ore at almost every other copper-mining district. The copper deposits occur in rocks of Precambrian age, in a thick sequence of northwest-dipping sandstones, conglomerates, ash beds, and flood basalts associated with the Keweenawan Rift. The first copper mines mined copper-filled fissure veins in basalt. Mining soon shifted to strataform native copper deposits in felsite-pebble conglomerates and in the upper zones of basalt lava flows (locally called amygdaloids).

Native copper industry

The Michigan State Geologist Douglass Houghton (later to become mayor of Detroit) reported on the copper deposits in 1841. Commercial production began in 1844. The first successful copper mine, the Cliff mine, began operations in 1845, and many others, such as the Minesota Mine, quickly followed. Copper mining in northern Michigan boomed, and from 1845 until 1887 (when it was exceeded by Butte, Montana) the Michigan Copper Country was the nation's leading producer of copper. In most years from 1850 through 1881, Michigan produced more than three-quarters of the nation's copper, and in 1869 produced more than 95% of the country's copper.^[2] Mining of the most productive deposit, the Calumet conglomerate, began in 1865. Mining took place along a belt that stretched about 100 miles southwest to northeast.^[3]

By the early 20th century, with a few exceptions, such as the Quincy Mine at Hancock, the mines in the Copper Country came under the control of two companies: the Calumet and Hecla Mining Company north of Portage Lake, and Copper Range Company south of Portage Lake.

Annual production peaked in 1916 at 266 million pounds (121 thousand tonnes) of copper. The native copper mines shut down in 1968, after producing 11 billion pounds (5.0 million tonnes) of copper.^[4]

White Pine mine

The copper-bearing Nonesuch Shale at the south end of the Copper Country in Ontonagon County had been known since the 1800s. But the ore grades were too low, the ore mineral particles too small, and the copper was largely in sulfides instead of native copper. All these conditions made the shale deposits uneconomic, although repeated attempts were made to mine the shale at the Nonesuch mine.

In 1955 the Copper Range Company began large-scale mining at the White Pine mine, near the old Nonesuch mine. The deposit is a strataform deposit predominantly of chalcocite in the Precambrian Nonesuch Shale. The White Pine mine, the last major copper mine in Michigan, shut down in 1995, having produced more than 1.8 million metric tons of copper.

The company applied to government agencies continue mining by in-situ leaching, using sulfuric acid to recover an additional 900 million pounds of copper by SX-EW. The Michigan Department of Environmental Quality approved the permit in May 1996, and White Pine installed a pilot in-situ leaching project.[1] Native Americans of the Bad River Indian Reservation in northern Wisconsin blockaded rail shipments of sulfuric acid to the mine (see Bad River Train Blockade); the mine began receiving acid shipments by truck. The US EPA, which had previously held that it had no role in the permitting, reversed itself, and stated that White Pine would have to apply for a federal permit. White Pine, which had already started to recover copper from the pilot project, suspended solution mining in October 1996, and applied for to the US EPA for the permit.[2] In May 1997 the company withdrew the EPA permit application, saying that further permitting delays had made the project uneconomic, and announced plans to begin reclamation of the mine site.

The tailings impoundment at the White Pine Mine is presently the site of significant environmental degradation. The University of Montana undertook extensive efforts to restore and revegatate the barren landscape from 1997-1999, but it is unclear whether this has been successful. The university has published a detailed report of its project.[3] Satellite images are available at (46°47′17.91″N 89°31′47.97″W / 46.7883083, -89.5299917).

Eagle project

Kennecott Minerals Corporation has proposed to open a nickel-copper mine called the Eagle mine project in the Yellow Dog Plains, about 25 miles northwest of Marquette, in Michigan's Upper Peninsula.

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