Some farmers call Iowa’s fertile soil “black gold,” but there may be real gold deep under all that dirt. University of Iowa researchers are studying core samples that could unlock secrets to valuable riches more than a thousand feet down. Ryan Clark, a geologist with the Iowa Geological Survey — an agency housed at the U-I, says indications show a potentially large formation of minerals well below the surface of ten northeast Iowa counties.

The core samples were taken during the 1960s by a company that was prospecting for iron. Geologists are now studying those samples to determine if it’s similar to a massive formation of precious minerals beneath Duluth, Minnesota.

The ten-county region being studied stretches from Decorah in the north, to Elkader and Manchester in the east, and as far west as Vinton.