A dormant Illinois volcano has rare earth metals. Scientists want to know why

Millions of years ago, there was a near volcanic eruption in southern Illinois.

“It did not actually erupt lava onto the surface,” said Southern Illinois University geologist Daniel Hummer. “The magma got really close to the surface. It sort of punched those topmost layers of rock upwards to form the dome.”

The now-dormant volcano is called Hicks Dome, and scientists like Hummer are fascinated by its geology, as it contains an unusual concentration of rare earth metals and radioactive minerals. Hummer hopes to better understand how it formed these materials.

“When you dig in and see what is under the surface on that hill, what you find are some very bizarre types of igneous rocks — igneous being the type of rock that forms from molten rock formed from magma,” Hummer said.

Hummer and his students have researched the site for several years. He specializes in crystal mineralization and regularly collaborates with other experts at the Illinois State Geological Survey for this work.

“When you're all going out there together and collecting samples and looking around, you end up putting everybody's expertise together to learn new things,” he said.

They’ve found radioactive materials like thorium in the rocks as well as many rare earth metals. These rare earth elements are economically important, as they’re used in manufacturing of electronics and other modern technologies.

Now, Hummer said they’re trying to figure out how much of these sought-after metals exist in Hicks Dome.

The dome has a gentle slope with a few houses built on top of it. Yet, it remains a place of interest mostly to the scientific community.

“It's been shrouded in mystery, and not a lot of people realize that this volcanic feature is actually in their backyard,” Hummer said.

For the full conversation with Daniel Hummer and to learn about what he has discovered about the dormant volcano in southern Illinois, listen to the full St. Louis on the Air conversation on Apple Podcast, Spotify, Google Podcast, Stitcher, or by clicking the play button below.

“St. Louis on the Air” brings you the stories of St. Louis and the people who live, work and create in our region. The show is produced by Miya Norfleet, Emily Woodbury, Danny Wicentowski, Elaine Cha and Alex Heuer. Ulaa Kuziez is our production assistant. The audio engineer is Aaron Doerr. Send questions and comments about this story to [email protected].