Study: Substantial Rare Earth Element Concentrations in North Dakota Lignite Coal Deposits

Highlights

• North Dakota State Geologist Edward Murphy discovered lignite coal samples with rare earth element concentrations over 4,000 ppm, significantly higher than the 300 ppm economic threshold.
• The study identified 18 high-concentration sites.
• The study proposes drilling 50 additional holes to assess the viability of REE extraction from coal deposits.
• Research indicates North Dakota’s lignite deposits contain valuable, heavy, rare earth elements.
• The lignite deposits potentially offer an alternative to current global REE sources.

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A recent study led by North Dakota State Geologist Edward Murphy (opens in a new tab) analyzed 2,200 lignite coal samples from North Dakota’s Bear Den and Rhame Bed formations, revealing rare earth element (REE) concentrations exceeding 4,000 parts per million (ppm) in some samples—well above the 300 ppm considered economically viable. Notably, these deposits contain both light and heavy REEs, including significant amounts of scandium, which is valuable for high-performance applications like aerospace components. The research team has identified 18 sites with high REE concentrations and proposes drilling 50 additional holes to further assess these beds’ viability.

The recent account was covered by Charles Crane, who was writing for the Minot Daily News (opens in a new tab).

There are two kaolin- or kaolinite-rich layers in North Dakota: the Bear Den Member of the Golden Valley Formation and the Rhame Bed of the Slope Formation. The Bear Den Member occurs stratigraphically above the Rhame Bed, and both are Paleocene in age. See the link for a geological map.

“When we started this project, the highest reported concentration of rare earths in the coal of North Dakota was 169 (ppm), and now we have samples over 4,000 (ppm). We think to be economic is anything over 300,” Murphy said. “It’s easier to get these rare earths out of coal or lignite because it’s not held very strongly.”

While the study highlights promising REE concentrations in North Dakota’s lignite, several pertinent questions remain unaddressed. Local news coverage does not delve into the potential environmental impacts of extracting REEs from lignite coal, nor does it discuss the economic feasibility and technological challenges associated with developing these resources.

Additionally, as Rare Earth Exchanges often highlight, these findings are not mentioned in relation to broader national strategies to reduce dependence on foreign REE sources, particularly from China. China currently dominates the global market. A comprehensive analysis of these factors is essential to fully understanding this discovery’s implications for the local community and the nation’s critical mineral supply chain.

In the recent piece, Murphy declared:

“The heavies are worth more than the lights are. North Dakota coals have some of the heavies. If you go just by costs, the rare earths in North Dakota coals are worth more than the rare earths coming out of Mountain Pass. The difference is they have more material to work with.”

Murphy said phase II of the project is on the table: drilling 50 more holes to explore the beds further and determine their viability,, reports Charles Crane at the local North Dakota newspaper.

Coal Deposits USA—North Dakota rich in Lignite