“SSMRC is uniquely positioned to become a major U.S. hub for critical minerals mining and processing,” said CEO Heather White. “In addition to producing its own metals, the project will also be capable of processing third-party concentrates, benefiting from our refining capacity.”
The company completed a $75 million equity financing round in September, led by its majority shareholder Electrum Silver US, to support development acceleration. The Sunshine project benefits from over $600 million in existing infrastructure and approximately $250 million in exploration and development investment since Electrum acquired the asset in 2011. The focus now is on advancing both the mine and the associated refinery toward production readiness.
The Sunshine refinery, which already has permits to process multiple metals, is being upgraded to handle antimony—a mineral classified by the U.S. government as critical to national security and energy resilience. Company projections indicate that the facility could meet about 40% of U.S. annual antimony demand by 2028, increasing to as much as 80% by 2031.
Antimony, a key component in semiconductors, munitions, and grid storage batteries, is currently imported primarily from China and Russia. U.S. authorities have designated it a high-priority mineral for domestic production to strengthen supply chain stability.
The Sunshine project also hosts one of the world’s highest-grade undeveloped silver deposits, with indicated resources of 112 million ounces grading 1,067 g/t. During its first five years of operation, production is expected to exceed 7.6 million ounces of silver annually, potentially raising total U.S. silver output by over 20%.
Located in Idaho’s historic Silver Valley, the Sunshine mine has produced more than 360 million ounces of silver since the early 1900s. Since acquiring the site, Electrum has expanded its land holdings fourfold and now controls the largest mineral rights package in the district. Ongoing exploration drilling has identified several new high-grade silver zones, indicating further potential beyond the existing mine plan.
Alongside the development of the antimony facility, SSMRC is advancing engineering and feasibility studies to modernize the mine’s hoisting system, surface structures, and water treatment operations. A full feasibility study is scheduled for completion in early 2027, paving the way for the project’s transition into construction and production phases.
The initiative positions SSMRC as a key player in strengthening the U.S. supply chain for critical and precious metals while revitalizing one of the nation’s most productive historic mining regions.
