Keewenaw Peninsula

The Keweenaw Peninsula (/ˈkiːwɪnɔː/ KEE-wi-naw, sometimes locally /ˈkiːvənɔː/) is the northernmost part of Michigan's Upper Peninsula. It projects into Lake Superior and was the site of the first copper boom in the United States. As of the 2000 census, its population was roughly 43,200. Its major industries are now logging and tourism, as well as jobs related to Michigan Technological University and Finlandia University.

The ancient lava flows of the Keweenaw Peninsula were produced during the Mesoproterozoic Era as a part of the Midcontinent Rift. This volcanic activity produced the only strata on Earth where large-scale economically recoverable 97 percent pure native copper is found.

Much of the native copper found in the Keweenaw comes in either the form of cavity fillings on lava flow surfaces, which has a lacy consistency, or as "float" copper, which is found as a solid mass. Copper ore may occur within conglomerate or breccia as void or interclast fillings. The conglomerate layers occur as interbedded units within the volcanic pile.

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