By Ernest Scheyder

(Reuters) -Perpetua Resources said on Thursday it is in talks with Glencore, Trafigura and others about a partnership to refine antimony in the U.S., part of a push to boost Western supplies of a critical mineral whose exports China has blocked.

The company, which counts billionaire John Paulson as its largest shareholder, last week received permission from the U.S. government to begin construction of its antimony and gold mine about 138 miles (222 km) north of Boise in Idaho.

The mine will be the largest U.S. supplier of antimony, which is used to make bullets, solar panels and other goods. There are no current U.S. sources of the metal.

Perpetua plans to extract the metal but not refine it, fueling a push to find partners for the necessary step.

The company said in a statement to Reuters that it is in talks with Glencore, Trafigura, Clarios and Sunshine Silver about a refining partnership and plans to seek proposals in the coming weeks with a decision expected by the end of the year.

"We are encouraged by emerging opportunities to expand domestic mineral processing capacity in America and intend to make well-informed, market-based decisions when selecting a partner," said Jon Cherry, Perpetua's CEO.

Glencore declined to comment. Sunshine Silver, Clarios and Trafigura did not immediately respond to requests for comment.

Perpetua's mine site has estimated reserves of 148 million pounds of antimony and 6 million ounces of gold.

The project has faced legal opposition from Idaho's Nez Perce tribe, which is concerned the mine could affect the state's salmon population.

Separately, United States Antimony, which controls two North American antimony refineries, secured a contract earlier this week worth up to $245 million from the U.S. Defense Logistics Agency to supply antimony metal ingots.

(Reporting by Ernest Scheyder; Editing by Muralikumar Anantharaman)