Rare earth minerals explained

Pre-mining exploration, studies still underway near Wheatland

By Lisa Phelps
Posted 5/1/24

WHEATLAND – Rare earth minerals, potential mining operations, and ongoing geologic research were discussed during a University of Wyoming community meeting April 17 in Wheatland.

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Rare earth minerals explained

Pre-mining exploration, studies still underway near Wheatland


WHEATLAND – Rare earth minerals, potential mining operations, and ongoing geologic research were discussed during a University of Wyoming community meeting April 17 in Wheatland.

While there has been a lot of talk about potential mine operations starting on the Albany/Platte County line, it will be several years before mining could commence, cautioned Sarra Stotter, MS, a geologist from American Rare Earths, Limited (ARE) assigned to the Halleck Creek project.

“You may be surprised how long it takes to go through the process to start a mine. There’s not going to be a mine in the ground this year. Probably not in five years – maybe in 10 years,” Stotter said. “There is a lot of work that needs to happen from now until then.”

That being said, Stotter and UW School of Energy Resources, Center for Economic Geology Research scientist, Dr. Lily Jackson, are excited at the prospects of the Halleck Creek project.

“There is only one rare earth mine in operation in the U.S.: Mountain Pass in California. There has been exploration in Wyoming [proving to be] very concentrated, and I can tell you from the bottom of my heart that Wyoming has the best geology of any state,” Jackson said.

She explained there are 15 rare earth elements, located at the bottom of the periodic table of elements. The deposit identified in the Laramie Mountain range of Wyoming meets all three requirements to be considered a critical mineral: it is a non-fuel mineral or mineral material essential to the economic and national security of the U.S.; serves an essential function in the manufacturing of a product, the absence of which would have significant consequences for the economy or national security of the U.S.; and has a supply chain that is vulnerable to disruption. Basically, China has always dominated the rare earth element market, and since rare earth elements are used in most modern technology that are required for our economy to function, it is deemed essential by the federal government to develop domestic resources to meet supply needs in case the supply from foreign nations is disrupted.

The name “rare” in the description of rare earth elements is a misnomer, as Jackson explained. “They are not rare in the sense they are not abundant. If you were to take all the gold in the world and all the REE in the world, side-by-side, you would have more REE than gold. Unlike gold, which tends to clump together in specific locations, REE tend to be widely distributed and dispersed.”

“The rare earth elements are found in extremely tiny concentrations, sometimes undetectable, and scattered around all the rocks of the world. To find concentrations of any rare earth mineral is extremely unique and very, very special. That’s why it is really exciting we have a substantially ore grade deposit right here in Wyoming,” Jackson said.

So, what is the difference between a rare earth mineral and a rare earth element? Rare earth minerals are host to one or more elements found on the rare earth elements list of the periodic table of elements. Some common things that use the rare earth elements extracted from the minerals are the magnetics used to run technologies such as laptops and cell phones, anti-lock brakes, microwave power tubes, communication systems, microphones and speakers, MRI’s, fiber optics, lasers, fluorescent lighting, medical imaging, steel, super alloys, NimH batteries, UV resistant glass, x-ray imaging, polishing compounds, pigments and coatings, capacitors, sensors, catalytic converters, petroleum refining, air pollution controls, fuel additives, satellite communications, guidance systems, aircraft structures, and smart missiles to name a few.

It’s a pretty long list, and ARE’s Halleck Creek project – with just 25 percent proved out – has resources containing a projected minimum of 2.34 billion tons of minerals containing 7.48 million tons of REE such as neodymium (Nd) and praseodymium (Pr). That adds up to what is being labeled by experts as potentially one of the largest rare-earths deposits in North America. There is another contender for REE near Upton, Wyoming, called the Mountain Pass deposit, but it is a different type of mineral out of a different rock type that is a high grade, but low tonnage deposit, Stotter said.

“What is really unique about our deposit is, it may be lower grade, but there is incredibly high tonnage – The Red Mountain plutonic rock deposit has varying mineralization throughout, but it is all enriched with REE. Our project is specifically two main areas: Overton Mountain area to the north and Red Mountain area to the south. We are focusing on these two areas, because they have the greatest mineralization and there is so much rock in the ground, honestly, we could never mine all of it, so there is no reason to research other regions of the pluton.”

In geologic terms, plutonic rocks or “pluton” are igneous rocks solidified by magma melt at great depth. As the magma rose, it brought minerals and precious metals with it, forcing them into the previously hardened volcanic rocks. In the case of the “Red Mountain pluton,” as the mineral is being referred to in local geologic circles, the anorthosite complex of the Laramie Mountain range (the parent magma) crystalized and had subsequent fractures (magma intrusions that forced elements into existing rocks), the last of which resulted in the allanite mineral containing the REE’s everyone is talking about.

Stotter said the anorthosite complex and REE host mineral, allanite, is a rare plutonic rock. “To explain it in simple terms, it is the last gasp of breath that crystalized – all the gases and minerals that were left over from earlier fractures finally found stability in the last hardening of the remnants of ancient magma,” Stotter said. “Allanite is the core mineral, but you can’t see it with the naked eye. It’s basically this really tiny mineral that gloms onto the edge of the black splotches, and you can’t see it with the naked eye. You can only see it with spectrometry (x-ray fluorescence spectrometry or XRF).”

Stotter had samples of the allanite-containing granite for people to see for themselves.

And, Jackson added as an interesting fact, the anorthosite complex is basically what lunar rocks are made of. “If you want to study moon rocks, you could come to Wyoming,” she said.

Located almost 19 miles southwest of Wheatland (44 miles northeast of Laramie) and right on the Platte County line bordering Albany County, ARE has ownership and mining claims of 367 unpatented lode mining claims and four Wyoming state mineral leases in Halleck Canyon. ARE’s subsidiary, Wyoming Rare (USA) Inc., controls the claims. Exploration drilling was conducted in the spring and fall of 2022 with promising results, then subsequent sampling in the fall of 2023 not only confirmed, but showed even better numbers for the quantity of rare earth elements in the Overton Mountain and Red Mountain granite deposits.

According to reports released in March, the project spans 8,165 acres, there are “exceptionally low levels” of radioactive elements, and, as Stotter explained, it is looking to be a best-case scenario in regards to being able to mine and extract the REE without major pollutants.

“I want to emphasize: no one would know how important this rock is just walking over it. It looks like boring old granite, but that’s what makes it unique and special with this project,” Stotter said.

Former UW alumni president and board member - and emcee at the university’s public meeting - Chuck Brown, said, “A few years ago, how many people ever heard of rare earth minerals or the REM / REE acronyms? And here we are right in the middle of it. There are so many things to think about.”

Currently, American Rare Earths is conducting scoping studies to further evaluate the potential viability of the mineral resources – including another drilling sample scheduled for this year – and analyzing the economic benefits and impacts of the Halleck Creek Project. A full state permit for the expanded area is expected to take one to three years, as one of many next-steps of development.

“I’m very excited, and we’ve got a lot of work to do in the next couple years,” Stotter concluded.