NYE, Mont. (AP) — The owner of the only platinum and palladium mines in the U.S. announced Thursday it plans to lay off hundreds of employees in Montana due to declining prices for palladium, which is used in catalytic converters.

The price of the precious metal was about $2,300 an ounce two years ago and has dipped below $1,000 an ounce over the past three months, Sibanye-Stillwater Executive Vice President Kevin Robertson said in a letter to employees explaining the estimated 700 layoffs expected later this year.

“We believe Russian dumping is a cause of this sharp price dislocation,” he wrote. “Russia produces over 40% of the global palladium supply, and rising imports of palladium have inundated the U.S. market over the last several years.”

Sibanye-Stillwater gave employees a 60-day notice of the layoffs, which is required by federal law.

Montana U.S. Sens. Steve Daines, a Republican, and Jon Tester, a Democrat, said Thursday they will introduce legislation to prohibit the U.S. from importing critical minerals from Russia, including platinum and palladium. Daines’ bill would end the import ban one year after Russia ends its war with Ukraine.

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The south-central Montana mine complex includes the Stillwater West and Stillwater East operations near Nye, and the East Boulder operation south of Big Timber. It has lost more than $350 million since the beginning of 2023, Robertson said, despite reducing production costs.

The company is putting the Stillwater West operations on pause. It is also reducing operations at East Boulder and at a smelting facility and metal refinery in Columbus. Leadership will work to improve efficiencies that could allow the Stillwater West mine to reopen, Robertson said.

The layoffs would come a year after the company stopped work on an expansion project, laid off 100 workers, left another 30 jobs unfilled and reduced the amount of work available for contractors due to declining palladium prices.