Copper Country History, Geography, and Geology While the title of this booklet focuses on "Copper Country," a treasure trove of different kinds of rocks and gems can be found on the Keweenaw Peninsula and the surrounding area; it truly is a rockhounding paradise! Of course, I'll also present you with information about the amazing copper that comes in so many different forms, shapes, and sizes. Most of the copper in the Upper Peninsula of Michigan (UP) was formed as pure copper, rather than as copper sulfides. This made it especially valuable from a commercial-mining perspective. In Precambrian times or almost 4.5 billion years ago, the copper formed within cooled lava masses (or basalt). Some of that copper weathered in what are referred to as float copper pieces or masses; some was mined out just as it formed. The geology term "float," refers to any material that's been moved by erosion, in this case glaciers of the Ice Age. The "glory days" of copper mining on the UP were in the late 1800s to early 1900s.

However, the first copper mine on the UP was established in 1771, and before that, Native Americans mined copper in this area as far back as 5000 BCE! While the heavy mining days came to an end in the mid 1900s, there is still some copper extraction happening with other mining activities--such as nickel mining--and giant float copper masses are still being found and sold for commercial uses. The largest "float copper" specimen ever found was 28 tons. Perhaps you might find a giant chunk of copper on your own hunt, like the 500-pound piece found, as shown in the bottom photo. I'll provide you with some geology and formation information for other types of rocks, minerals, and gemstones as we go through the different sections for each type of stone.