Coal, Research

Critical Minerals in North Dakota’s Shales

This Energy & Environmental Research Center (EERC) project, funded through our designation as the State Energy Research Center (SERC), focused on evaluating North Dakota shales as a potential resource for rare-earth elements (REEs) and other critical minerals (CMs). The demand for these high-value materials has increased in recent years with the expanded personal and commercial use of high-tech devices such as smartphones, computers, and televisions as well as for military applications and green energy uses. The United States is heavily reliant on imports of these mineral commodities, which are vital to our national security and economic prosperity. To meet the demand and reduce our dependence on imports, the President of the United States issued Executive Order 13817 in December 2018 to identify new sources.

Preliminary findings from previous studies showed high levels of REEs in some Bakken shales. However, discussions with the North Dakota Geological Survey indicated that very few data exist on REEs and CMs in other North Dakota shale formations. Hence, the goals of this project were to characterize shale resources in the state of North Dakota that may have elevated levels of CMs and identify proxy metals to better understand the thermal maturity and depositional environment of source rocks.

For this project, a total of 78 North Dakota shale samples from three different formations (Niobrara, Pierre, and Bakken) were evaluated for total REE (TREE) and other CM content.

The results showed that a relatively high percentage (9.3%) of the 43 Niobrara and Pierre samples collected in this project had TREE levels >300 ppm, which is the level assigned by the U.S. Department of Energy (DOE) as the concentration required to be considered a viable feedstock for extraction and concentration of REEs.

In addition to evaluating shales as a potential CM resource, many of the metals included in this characterization effort can also serve as key indicators of the paleodepositional environment of the various formations. These metals include, but are not limited to, aluminum, cobalt, copper, chromium, lead, molybdenum, nickel, vanadium, and uranium. This novel approach to determining depositional environment and thermal maturity could help support more conventional methods used for characterizing and understanding shale source rock potential and identifying promising new sources of oil and gas. Some proxy metals (copper, cobalt, molybdenum, vanadium, and uranium) showed positive correlations with organic carbon, with the Pierre shales having a higher correlation than the Niobrara. More sampling and analysis are recommended to confirm these correlations.

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