Witnesses urge national mine-waste inventory and mill-sampling campaign to recover critical minerals

Multiple witnesses told the subcommittee that Earth MRI's geophysical mapping should be paired with systematic geochemical work to unlock value in legacy mine waste and support Good Samaritan remediation.

Dr. Elizabeth Holly, a professor at the Colorado School of Mines, said the United States lacks a comprehensive federal dataset on mine and mill geochemistry and recommended a national ore-sampling and mill-sampling campaign. "For the majority of U.S. mines, we do not even have geochemical data from a single rock," Holly said, arguing that targeted sampling could reveal byproduct recovery opportunities that would reduce supply-chain vulnerability.

USGS witness Dr. Colin Williams described the National Mine Waste Inventory already under development and said the agency has identified subsets of legacy features likely to be mine-waste and is collaborating with states to characterize volumes and material composition. Representative Lee, who represents Nevada interests, noted the Good Samaritan remediation pilot at EPA and asked about compatibility gaps; Williams said USGS supports EPA by providing scientific data and that agencies are working through permitting and coordination.

Panelists emphasized that data alone do not authorize development: mapping and sampling inform permitting and remediation options but permitting agencies determine whether projects proceed. Witnesses urged that reauthorization language includes funding for these targeted geochemical efforts and for the scientific ecosystem (state surveys and university partnerships) needed to analyze samples and scale remediation and recovery pilots.