The Keweenaw peninsula in the upper peninsula is the site of the most extensive known deposits of native copper in the world. Occurring here in relatively pure form, Keweenaw copper was mined for approximately 7,000 years, from 5000 BCE until 1968. During the period for which records were kept, 1840–1968, more than 11 billion pounds of copper were mined here.
Of particular interest is “float” copper which was ripped out of the ground and transported (“floated”) here by ice age glaciers. It is 99% pure and has been found in chunks weighing as much as 28 tons. One mine bankrupted 3 owners because they couldn’t figure out an economical way of biting off small enough chunks of pure copper to get it out.
Mineral Museum, Keweenaw National Historical Park, and Hungarian Falls
