Hidden Coal Riches

The key to a carbon-neutral future may be buried deep in America’s coal country. U researchers have discovered significant concentrations of rare earth elements (REEs), critical for clean energy tech, near coal deposits in parts of Utah and Colorado.

“The rare earths are concentrated in the muddy shales above and below the coal seams,” says study co-author Lauren Birgenheier, associate professor of geology and geophysics. “If mines are already moving rock, could they shift operations to also extract these resources vital for the energy transition?”

REEs such as neodymium and dysprosium, essential for wind turbines, EV motors, solar panels, and electronics, are largely imported from China. These 17 metallic elements, mostly found among the lanthanide series, reside in the third column and sixth row of the Periodic Table. The U.S. uses more than 8,000 tons of rare earth oxides annually, nearly all from ores processed in China.

In partnership with the Utah and Colorado Geological Surveys, the U team analyzed rock samples from the region’s coal mines. They discovered REE levels often approaching 300 parts per million, the federal threshold for economically viable extraction.

“We’re trying to find alternative, unconventional domestic sources for these critical minerals,” says Michael Free BS’90 MS’92 PhD’94, a professor of metallurgical engineering and leader of the Department of Energy-funded project.

With promising results from 11,000 total samples so far, the researchers are seeking additional federal funding to quantify the size and quality of these REE deposits. They theorize that the rare earths, once concentrated in ancient peat bogs that became coal deposits, have migrated over time into adjacent rock layers.

The recent discoveries raise hopes that this iconic coal region, long vital for powering the nation, may play a key role in America’s clean energy revolution.