The Ontonagon Boulder is a 3,708 pound (1682 kg) boulder of native copper originally found in the Upper Peninsula of Michigan, United States, and now in the possession of the Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution. The boulder is a relic of the mining rush to the Michigan Copper Country, and was well known to Native Americans in its location on the west branch of the Ontonagon River, in what is now Victoria Reservoir. According to the Keweenaw Bay Indian Community, the boulder was used by tribe members to make offerings to its manitou (spirit) and to seek improvement in their health and well-being.