I'd at least give it a few hours. There's museums on site that'll tell more about the place as well. There's lakes you can kayak in and presumably fishing.
2 hours minimum if you take the tour
In Tower, southwest of the mine on RT 1, there is a great train exhibit. Very helpful information board. The mine itself has a lot to see if you're interested in mines. Lots of buildings to look through and the mine itself. Then there are a few hiking trails.
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