Highlights

• The historic Stibnite Mine in Idaho reopens, promising to supply up to 35% of U.S. antimony needs for defense systems and munitions.
• Perpetua Resources aims to restore an abandoned mining site while addressing national security mineral supply chain vulnerabilities.
• The mine's restart represents a strategic effort to reduce U.S. dependence on Chinese mineral exports and strengthen domestic resource production.

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The United States took a significant step toward shoring up its fragile mineral supply chains last week with the reopening of the historic Stibnite Mine in central Idaho. The Pentagon hailed the restart as a milestone in its drive to rebuild domestic access to critical inputs — especially antimony, an element central to munitions and advanced defense systems.

From Dormancy to Deployment

At a ribbon-cutting ceremony on September 19, Maj. Gen. John T. Reim, head of the Army’s Joint Program Executive Office for Armaments & Ammunition, declared the reopening “one step closer to establishing a complete domestic supply chain.” The mine, operated by Perpetua Resources (opens in a new tab), has been idle for decades. After eight years of permitting reviews and more than $400 million in investment, it is now poised to deliver again.

Perpetua’s filings with the U.S. Forest Service indicate Stibnite’s ore contains not only gold and silver but also 149 million pounds of antimony— enough to eventually meet up to 35% of U.S. demand. The scale makes the project one of the largest antimony reserves outside foreign control.

Antimony: A Strategic Mineral

The Pentagon’s interest is straightforward. Antimony (opens in a new tab) is used in armor-piercing ammunition, primers, tracer rounds, hardened metals, infrared optics, flares, and even nuclear weapons production. During World War II, Stibnite alone supplied roughly 90% of the U.S. military’s antimony needs. Yet the mine went quiet in the 1990s as Washington leaned into foreign supply chains — today overwhelmingly dominated by China.

That reliance has become untenable. Beijing’s export restrictions on critical minerals earlier this year exposed the Pentagon’s vulnerability, forcing planners to confront the risks of depending on an adversary for warfighting materials.

Policy and Supply Chain Reset

Perpetua CEO Jon Cherry framed the reopening as both an industrial and environmental project, restoring an abandoned site while delivering “resources urgently needed for national security.” Maj. Gen. Reim tied it directly to the Army’s “Ground-to-Round” munitions strategy, which aims to secure raw materials, processing, and production entirely within U.S. borders.

The Biden administration committed to a “whole-of-government” effort to reshore supply chains back in 2021, but progress has been slow. The drawn-out Stibnite permitting saga underscored just how difficult such projects remain in practice. The Pentagon now sees the restart as evidence that momentum is shifting.

Strategic Signal

Once Perpetua posts its joint financial assurance bond in the coming weeks, mining operations will resume this fall. For Washington, the message is clear: antimony, long overlooked in favor of gold and silver, is a strategic asset. As tensions with Beijing continue, every ton mined in Idaho represents less leverage for China and more resilience for America’s defense industrial base.

Source: “Pentagon Hails Restart Of Critical Minerals Mine In Idaho,” Forbes, September 21, 2025

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