Most rare earths on earth? 

CASPER — A mine exploration project in Halleck Creek was ranked as one of the top ten critical mineral sites on the planet after assay results earlier this year revealed exceptionally high levels of rare earth elements. 

But this month the project owners, American Rare Earths, U.S. subsidiary of an Australian-founded exploration company, have completed their full development drilling campaign, and the new assay results suggest that soon this Albany County mine will be ranked number one. 

Mineral testing of samples from Overton Mountain revealed the site contains even higher concentrations of minerals at even greater depths than originally expected. And with its mineral deposits still “open at depth,” the bounty could just keep getting bigger.

“I’ve been in and around mining for 25 years and it’s not often when you’re doing developed drilling that the resources gets bigger…and higher grade…” said Donald Swartz, CEO of American Rare Earths (ARE), explaining that holes as deep as 1000 ft. showed a 24% increase in mineralization over previous assays, bringing averages to 4179 ppm total rare earth oxides (TREO), with some samples as high as 11,040 ppm.

“The program proved that [the deposit] is continuous, not intermittent, that it’s a higher grade than we thought and much deeper and bigger than we thought.” 

The target minerals are neodymium and praseodymium, known as magnet metals, which are vital for the production of automobiles, computer technology and national defense systems. 

The results come at a time when domestic deposits are deeply needed, according to industry experts, as critical mineral supply chains have consolidated in China, which currently accounts for 60% of the globally-mined magnet minerals and as much as 91% of their processing and manufacture, according to the Center for European Policy Studies. 

The concern is compounded by the fact that magnetic minerals are an indispensable component of national defense technology, and with geopolitical tensions mounting between rival superpowers, security experts are urgently pushing for the development of resources like those at Halleck Creek. 

“These are these elements most critical in national security … for submarines, aircraft carriers, drones, advanced weapons systems, which currently we’re sourcing from China. That’s really been the whole driving force behind the government trying to reshore this stuff, and we think we’re uniquely positioned to do that,” said Swartz.

Beyond raw volume, the Halleck Creek deposits are additionally valuable because of their unique composition and relative purity, namely, low “radioactive penalty.”

Critical minerals are typically coupled with radioactive elements, like uranium and thorium, which must be scrubbed out, often at high expense. The deposits’ unique geologic origins — an igneous extrusion created by internal earth processes and pushed to the surface by seismic activity — that have resulted in the deposit having its radioactive elements washed away naturally. 

The latest assays also indicate the Wyoming deposits are highly homogenous, allowing for greater efficiency in processing. 

Unlike many critical minerals locked up in “hard rock,” these deposits are hosted in softer material more akin to clay, according to company geologists. Mountain Pass Mine in California, for instance — the only commercial critical mineral mine in the U.S. currently — relies on a “cracking circuit” that involves large rotary kilns in concert with caustic acid solution, an expensive and tech-heavy process. 

But because the Halleck Creek deposits are minimally radioactive, highly homogenous and accessible in clay-like holdings, it allows the magnet metals there to be easily captured through atmospheric acid tank leaching — a low-risk and cost-effective separation process — as shown in preliminary metallurgic testing done by the company. 

“What’s really unique about this deposit is that the uranium and thorium have been weathered away, which makes the processing simpler,” Swartz said, “but the real secret sauce is the processing where you can direct-leach it.” 

Halleck Creek will benefit also from access to interstate roads along with Burlington and Union Pacific rail lines which run on either side of the mine site through Wheatland and Laramie, respectively. 

The project’s viability is facilitated further by the state’s mining-friendly culture and navigable regulatory environment, along with ready-order experienced miners in state. 

The company for now is focused on commercializing extraction, but as the domestic industry expands ARE hopes to take a bigger role in the supply chain. 

“Once [the U.S.] explores the processing and refining, there’s no reason that it can’t all be co-located in a place like Wyoming. All the pieces have started to come together and it makes Wyoming for a lot of reasons a really attractive place to do this,” said Joe Evers, general counsel for ARE, who was raised in Sheridan. “Wyoming has the people to get it done, the knowhow, and there’s regulatory efficiency that puts us in a good place. So why not Wyoming, why not us and why not now? I think this is a generational type of opportunity.”