Geology and Mineral Deposits of the Keweenaw Peninsula and Vicinity, Michigan

The area of this data set includes the classic geology and mineral deposits of the Keweenaw Peninsula, renowned for the occurrence of great volumes of Middle Proterozoic flood basalts and the world's largest concentration of native copper. Native copper was mined there continuously from the 1840's to the 1960's. For the earlier part of that period the Keweenawan native copper district was the principal source of copper for the United States.