United States Antimony restarts mining in Montana

United States Antimony Corp. (NYSE: UAMY) said on Thursday it has resumed mining at its Stibnite Hill property in Montana following a near five-month halt.

In November, the company announced it had ceased activities at the site due to weather conditions. The halt came just weeks after it began mining raw ore from Stibnite Hill for sampling at a flotation mill in Radersburg following Montana state approval.

The plan is to process the material into antimony concentrates and then transport them to USAC’s existing smelter in Thompson Falls, where they will be turned into finished products and sold to its customers.

Antimony has several key industrial uses, among which are defense applications such as flame retardant fabrics, communication equipment, night vision goggles, ammunition and laser sighting. The US has no mined production of antimony, and therefore relies on foreign suppliers such as China for the critical mineral that its military uses.

USAC’s Thompson Falls site is currently the only antimony smelter in the US. It also holds the only other antimony smelter in North America: Madero in Mexico.

With the start of operations at Stibnite Hill — a former mine that operated for 15 years from the late 1960s to early 80s — the company is looking to establish itself as the first fully integrated antimony operation outside of China and Russia.

On its website, USAC noted that its Thompson Falls smelter can produce approximately 15 million lb. of antimony oxide or 5 million lb. of antimony metal per year, and an expansion is underway to boost that production capacity.

2026 mining program

During last year’s mining period, approximately 800 tons of antimony ore were brought from the mountain to the Radersburg facility, USAC has noted. In October, the company said there were early indications that the material could be upgraded to meet military specifications.

The restart, according to the company, was earlier than expected due to “milder weather conditions” and “minimum snowfall” in Montana.

This year, USAC is also looking to make several changes to its mining program, including the use of a chipper for the smaller brush and branches to produce a mulch that will be used in the concurrent reclamation program.

This will aid in faster re-vegetation while providing better access to existing roads and trails where 2026 mining activities are commencing, it said.

The company also said it plans to establish base stations on adjacent mountain tops, where GPS transmitters will be set up so that its field crews can use portable data collectors for more accurate mapping and recording of antimony vein intercepts, enabling the projection of antimony veins on strike and down dip.

Shares of United States Antimony advanced 4.5% after announcing the restart of mining, erasing its losses for the week. The company, which recently uplisted to the NYSE, has a market capitalization of $1.2 billion.