Freeport-McMoRan, Rio Tinto and BHP are among the miners testing sulfide leaching as tariff threats send copper prices ...

In Arizona alone, the Department of Environmental Quality estimates that between 40,000 and 100,000 abandoned mines could be scarring the landscape, although a full inventory has never been completed.

And if and when these old mines are cleaned up, the cost burden usually falls on the American public. Even more disconcerting is the toxic legacy left on public lands and sacred American Indian sites.

Officials promise safety with a southern Arizona mine that is on track to start production in 2027, while community health ...