I’m a mining engineer.
The cost of production in the U.S. Is too high due to excessive regulation, lawsuits of no merit by environmentalists, and dumping by China. Currently it takes over 10 years to get the necessary environmental permits for a mine and it’s just not cost effective to wait that long.
Don’t believe me? Do an Internet search for Rosemont copper mine or Resolution mine.
Taxes are another reason. A large copper project was in the planning stages in Wisconsin.
An AG-ECON socialist professor convinced the state that punitive extraction taxes were justified. He cited a flawed computer program that over stated profits and ignored inflation.
The legislature passed the taxes, and the mine was never developed.
On the Wisconsin Crandon project, Exxon lost millions in exploration and development costs.
Part of the problem was the project was opposed by radical element of the local Indian tribes. The land for the mine, which was to be an underground project, was not even on the reservation.
Or the Pebble Mine project in Alaska. What a sad and expensive story.
Pebble Mine
https://en.wikipedia.org/wiki/Pebble_Mine