USGS Confirms Dark Monazite at US Rare Earth’s Lemhi Pass

US Rare Earths (OTCQB:UREE) reported that the United States Geological Survey has confirmed the presence of dark monazite at US Rare Earth’s Last Chance mine. The company has demonstrated that dark monazite has lower potential processing costs.

The Last Chance Mine is located in the Lemhi Pass Area of Idaho and Montana, and it contains one of the longest identified mineralized veins in the region. The Lemhi Pass area has been identified as having over 200 mineralized veins. The company holds 140 claims in the Lemhi Pass area which cover a significant number of these historically known mineralized veins.

The United States Geological Survey (USGS) has identified the presence of Dark Monazite at the Last Chance Mine. This unique mineralization, enriched in the mid-rare earth elements (particularly Europium) provides multiple avenues for continued process innovation, with the potential for a very significant reduction in acid consumption compared to other deposits’ processing methods, the company said. Acid leaching in Rare Earth processing typically adds a significant contribution to the operating costs.

Speaking to metallurgical testing completed at the project, the release stated:

In summary the work to date indicates that the main high-value rare earth minerals are Dark Monazite, enriched in Neodymium, Europium, and Xenotime (an Yttrium Phosphate mineral).

Moreover, early liberation and magnetic separation tests indicate that the cost of grinding the mineral will be lower than expected, because less than 0.1% of Total Rare Earths (TREE) plus Yttrium stays in fractions larger than +14 mesh, allowing for the possibility of a considerable reduction in material grinding for beneficiation. Grinding is typically one of the major contributors to processing cost.

The initial results of magnetic separation work potentially allows the company to process only 38% of the bulk weight, with approximately double the “as-mined” rare earth concentration. Recoveries were in excess of 92%.

The recovery rate of the following assayed rare earths, based on feed to testing, was Lanthanum 94.1%, Cerium 94.1%, Neodymium 93.8%, Praseodymium 93.8%, Samarium 88.2%, Europium 92.8%, Gadolinium 91.6% and Yttrium 93.1% in 38% of the feed. The heavy rare earth fractions were not assayed at Hazen Research during these initial test sequences. The company anticipates that further metallurgical testing can improve on these results significantly.

The company believes downstream leaching acid consumption and processing costs will be greatly reduced from this result.

Multiple leaching tests were conducted independently by Hazen Research and SGS Mineral Services Canada on non-magnetically concentrated bulk sample material. Rare Earth extraction yielded recoveries of 79-78% for the light to heavy rare earth fractions and demonstrated the technical feasibility of higher recoveries. Continued optimized testing is anticipated by the company to improve these recoveries and future leaching tests will benefit from using the magnetic concentrates developed at Hazen Research.

Dr. Virginia Gillerman of the Idaho Geological Survey’s (IGS) team

The entire Lemhi Pass district is enriched in mid-rare earth elements, and our team successfully used lab-scale standard crushing, gravity separation, and stepwise magnetic separation to provide a monazite fraction for detailed scanning electron microscope and microprobe analysis.

US Rare Earths CEO, Kevin Cassidy, said:

The metallurgical tests proving the Dark Monazite component of the mineralisation have come back with results far beyond our expectations. This met work is the key preliminary development work to move the Last Chance Project towards a low-cost, proven and feasible project. These works, moreover, provide a viable road map for continued improvements in beneficiation in follow-up and advanced work.

Click here to read the US Rare Earths (OTCQB:UREE) press release