The US opened a pilot plant to turn Idaho antimony into ammunition

Perpetua Resources, the US Army and Idaho National Laboratory opened a modular pilot plant to turn ore from the Stibnite Gold project into military-grade antimony trisulfide. It's the first concrete step to reduce US dependence on China and Russia for this mineral.

Perpetua Resources, the US Army and Idaho National Laboratory (INL) opened, on July 29, 2026, a modular mineral processing pilot plant in Idaho Falls. The unit processes ore samples trucked in from the Stibnite Gold project in central Idaho — a district that already supplied the United States with antimony and tungsten during World War II and today holds the only identified antimony reserve on US soil. The stated goal is to demonstrate, at small scale, domestic production of military-grade antimony trisulfide, used to manufacture ammunition and other specialized industrial applications.

Rebuilding a critical mineral supply chain from scratch rarely starts with a commercial-scale refinery — it starts with a pilot plant small enough to prove the metallurgy works before any larger capital commitment. That's exactly the role of the Idaho Falls unit: validate whether Stibnite antimony can be refined to the purity grade required for military applications, before any decision on building industrial-scale capacity. The funding behind the project also teaches something about how the US government builds this kind of strategic bet today: instead of a single funding line, the $87 million invested in Stibnite since 2022 comes from distinct sources stacked together — $59 million from the Defense Production Act, Title III, an additional award from the Defense Ordnance Technology Consortium, and $27 million directly from the Army through an ordnance technology initiative agreement. It's a mosaic of public funding instruments, each designed for a different stage of project maturity, not a single check. There's also a lesson about what exactly counts as a critical mineral in practice: it's not raw antimony that matters here, it's a very specific chemical form of it — military-grade antimony trisulfide — that China stopped supplying to the United States in 2021. Strategic vulnerability often lives at that level of specificity in the final product, not in the generic availability of the raw material.

The Stibnite case works as a replicable model for any country that needs to reduce external dependence on a strategic mineral without unlimited capital: identify the existing domestic reserve, validate the metallurgy at pilot scale funded by multiple public programs, and only then move to commercial scale. For anyone evaluating a career or investment in mineral processing in the United States, the plant's modular design — built to be reconfigured and test other critical mineral processing flowsheets — also signals where the next wave of government-funded pilot projects is likely to appear.