The rocks of the Keweenaw Peninsula are ancient and full of history. Most are more than one billion years old and hold one of the world’s few native copper deposits. In their guest blog, part of a series on local geoheritage, Erika Vye and Bill Rose explain the importance of a single Copper Country boulder.
The North Houghton County Sewage Authority hit a boulder during work south of Calumet. The boulder is large—nearly seven feet across—but that’s not what makes it unusual. The rock type is a rare sight at the surface and is chock full of copper. The rock is part of the Calumet and Hecla Conglomerate, a formation considered the mother lode of the Keweenaw Peninsula, and represents an important part of the region’s history.