On a sunny day last week in Michigan’s Upper Peninsula, Kevin Sundholm picked up a small handful of marble-sized pellets of iron ore from the ground. “Those pellets would go through there and they would get baked,” he said, gesturing at the abandoned foundations of the former Groveland Mine complex near Felch, in Dickinson County. “You can see the remnants up on top of the silos there,” Sundholm said. He knows the lay of the land. He worked here more than 40 years ago. For decades, the complex