Exploring Copper and Iron Country

Mines, Museums Minerals of Michigan’s Upper Peninsula

- SUE EYRE

In the mid-1800s, the discovery of large deposits of copper and iron attracted thousands of miners to settle in the Upper Peninsula (UP) of Michigan. These same mineral deposits had previously been discovered by Native Americans thousands of years before and used to make tools, jewelry, and ceremonial artifacts. Today, rockhounds visit this area, not only to collect Lake Superior agates and fluorescent sodalites, but many are drawn to immerse themselves in the history and culture of the copper and iron industries that built this part of Michigan.

Let’s take a look at a few of the UP’s mines, museums and unusual minerals that are often found in association with these native copper and iron deposits. A visit during Keweenaw Week in August may even provide an opportunity to collect samples from mines not usually open to the public, visit a local club’s rock and mineral show or attend a special event at a world-class museum.

GLACIAL DEPOSITS

The metamorphic and igneous rocks of the UP are some of the oldest on earth. Ancient, iron-rich sea beds and Midcontinent Rift volcanism before the Ice Age, contributed to the presence of both ferrous minerals (iron ore) and non-ferrous, metallic minerals (copper, nickel, silver and gold) in this part of Michigan.

During the Ice Age, thick layers of ice advanced and retreated multiple times over the entire Great Lakes area, scraping, scouring, depositing and moving native copper, silver, iron and a host of other minerals, leaving deep depressions that filled with glacial melt-water, creating the Great Lakes and a rockhounding paradise concentrated in the UP of Michigan.

The main copper deposits were found in the Keweenaw Peninsula, as well as Isle Royale. Two major iron deposits were located to the south, in the Marquette and