The Keweenaw is the only place on Earth where copper occurs in commercial quantity as pure metal rather than ore, in sheets, wires and single masses that ran to five hundred tons. People have been cutting it out of this rock for seven thousand years, the oldest metalworking on the continent. The Delaware Mine at Mohawk is an 1840s working you can walk into, self-guided, the first level lit, with rock piles above ground where visitors are allowed to hunt. PUBLIC tour with collecting on site; the surrounding land is mostly private or corporate, so ask before you swing a hammer anywhere else.
Native copper, silver, datolite
See it on the map
Other places on the map within a couple of hours.