New copper and nickel mining on Minnesota’s Iron Range promises to bring in more than $1 million and hundreds of jobs to the state, but precious metal mining can produce sulfuric acid, which can cause environmental damage.

Lawmakers want assurance that new mining will be safe.

"There's not a good track record. We don't have much trust in the industry. There are a lot of financial incentives to walk away from problems," said Clyde Hanson of the Sierra Club.

Canada-based Polymet Mining already bought a mine near Babbitt, Minn., and has requested permits to begin operations by the end of this year.