Which major metal was extensively deposited in the Keweenaw Peninsula?

The Keweenaw Peninsula, located in Michigan, is renowned for its significant deposits of copper, which have played a crucial role in the region's mining history. Copper was formed through volcanic activity and the subsequent cooling of magma, resulting in the rich mineral deposits found in the area.

In the mid-to-late 19th century, it became one of the most important centers for copper mining in the United States, contributing substantially to the economy and development of the region. The copper mined from the Keweenaw Peninsula was used in various applications, especially in electrical wiring and other technologies, which further illustrates its importance.

While the other metals listed have their significance in different contexts, copper is distinctly associated with the geological and historical narrative of the Keweenaw Peninsula, positioning it as the correct and most relevant choice in this context.