Copper and Copper Compounds

For the past 6000 years copper from northern Wisconsin and the upper peninsula of Michigan has been utilized by various peoples. Jewelry and tools made from copper produced in this region have been found as far away as the Gulf Coast and the Rocky Mountains. Native Americans and early French explorers found huge chunks of copper along the shore of Lake Superior. Today, geologists believe significant copper ore deposits still exist in Wisconsin, though not as easily accessible as those native (pure) copper chunks found hundreds of years ago.

Figure 1 - Copper Artifacts from the upper peninsula of Michigan

courtesy of Michigan Tech University Archives

The copper deposits that first attracted white and European settlers to the southern shore of Lake Superior were called native copper deposits. These deposits were formed over 1 billion years ago when superheated water from volcanic activity in the region dissolved copper minerals. Over time, the hot water cool and allowed the copper to precipitate as pure copper in certain layers of rock. These native copper beds of the Keweenaw Peninsula yielded large sheets of copper weighing sometimes in excess of over 1000 lbs.

Figure 2 - Metals Deposits in the Upper Peninsula

The discovery and mining of copper spurred the settlement and growth of the western Upper Peninsula in Michigan during 1840’s to 1860’s. Towns like Ontonagon, Copper Harbor, Houghton, and Calumet were settled and played a role in copper economy of the area. Michigan Technological University (Michigan Tech) was formed and still today has trains students in engineering, geology, and other mining related fields. Large shipping ports were built in Copper Harbor and Houghton-Hancock to transport copper and iron to other regions.

Today, little native copper remains. Most copper is found in the form of copper ores or copper in an ionic compound. Chalcocite, known as copper sulfide (Cu₂S) chemically is the most important copper ore. Up to the late 1990’s two copper sulfide mines were active in the Upper Midwest. The White Pine in the Upper Peninsula and the Flambeau Mine in Ladysmith, Wisconsin operated. As recently as 2004, proposals were drafted to build a mine outside of Crandon, Wisconsin to extract copper and zinc from a large deposit buried beneath the glacial deposits in the area.