By Ian Foreman
Appia Rare Earths and Uranium Corp. (API:CSE, APAAF:OTCQX, A010:F) has been diligently delineating a high-grade critical rare earth elements and gallium deposit at its Alces Lake property, as well as exploring for high-grade uranium in the prolific Athabasca Basin. In total, Appia holds the rights to 113,837.15 hectares in Saskatchewan. The company also has a 100% interest in the 12,545 hectare rare earth element and uranium Elliot Lake property located in Ontario.
It is, however, their acquisition of the PCH Project in Brazil that has garnered the bulk of the attention lately. A shift to South America wasn’t taken lightly, but the potential asset there could dramatically change the company’s future.
On June 9, 2023, Appia announced the right to acquire a 70 percent interest in the PCH Project in Goiás State, Brazil. The property is host to at least one ionic clay hosted rare earth element (or ‘REE’) deposit.
“Appia has taken a significant step in cementing itself among the upper tier of critical mineral explorers with [this acquisition],” stated Stephen Burega, President of Appia.
The Company’s due diligence review revealed remarkable geological prospects, outstanding assay values, and further expansion potential. “The exploration work by the vendor showed REE enrichment in the soils to depths of 8 to 26 m with the majority in the upper 8-10 m. Total REE grades in numerous auger holes drilled at Target 4 ranged from 274 ppm to 16,648 ppm (1.66%), with an average of 1,291 ppm total REE ….”, stated Mr. Don Hains, senior consulting geologist and Qualified Person for Appia. “The assays demonstrated rare earth enrichment in the upper 8 to 10 metres, with depleted cerium in the top 1 to 2 metre interval. These are classic characteristics of ionic clay enriched REE deposits as found in China and in deposits in Brazil such as Serra Verde”, concluded Mr. Hains.
Since acquiring the PCH Project, Appia has completed a significant work program that included 147 reverse circulation drill holes. Management is thrilled with the initial results as assays reported to date have exceeded expectations. The PCH ionic clay project has shown its significant potential with impressive distribution, width and grades of REE mineralization.
An overview of rare earth elements – REEs and REOs
REEs are a group of 14 elements that are classified as lanthanides. As such they share many similar properties that often cause them to occur together in nature. Despite their name, many REEs are not rare and are, in fact, abundant in the Earth’s crust. According to clearias.com, they are so-called ‘rare earth’ because they were originally isolated in the 18th and 19th centuries as oxides from ‘rare minerals’ and their separation was considerably difficult at the time. In essence, the name they got in the 18th century has stuck with them.
REEs are generally divided into two subsets: light rare earth elements (LREEs) and heavy rare earth elements (HREEs). LREEs, including elements like lanthanum and neodymium, have lower atomic numbers and are more abundant in the Earth’s crust compared to HREEs. HREEs, such as dysprosium and terbium, have higher atomic numbers and are generally scarcer.
A growingly important sub-set of REE’s are Metal (or Magnet) Rare Earth Elements (MREEs), which are REEs such as lanthanum, cerium, praseodymium and neodymium that are combined with other elements such as strontium, barium or calcium. This combination enhances many of the mineral’s properties, which enhances their stability, conductivity and catalytic activity. These improved characteristics make MREEs more versatile for applications in electronics, catalysts and renewable energy technologies.
REEs have diverse industrial applications as their unique properties contribute significantly to the functionality and efficiency of modern technological applications across various industries. One of the most important uses is in the manufacturing powerful magnets for electronics, such as in electric vehicle motors and wind turbines. REEs also are vital in the production of catalysts for petroleum refining and play a crucial role in phosphors for energy-efficient lighting. In addition, REEs are also employed in electronics, glass polishing, and as essential components in a range of advanced technologies, including smartphones, computers, and medical devices.
The REE market is dynamic as prices fluctuate in response to geopolitical tensions, environmental regulations affecting mining, and technology advancements that are driven by increasing demand for high-tech products. As strategic resources, REEs impact economic and industrial strategies worldwide, prompting countries to secure stable supplies and explore recycling solutions to mitigate dependence on primary sources.
REEs are distributed globally, with China historically dominating production, supplying over 80% of the market. Other significant producers include Australia, the United States, and countries in Africa. Geopolitical concerns have led to efforts to develop additional sources of REEs. Brazil possesses significant REE deposits, primarily found in the states of Minas Gerais and Goiás, which positions Brazil as a growing important player in the global REE market.
The oxidized REE’s are, in turn, are abbreviated to REOs. As a result, the concentration of REEs in secondary deposits such as ionic clays are reported as REOs. Results reported as REO can sometimes not include yttrium oxide.
An introduction to ionic clays
Ionic clay refers to a type of clay with charged particles, or ions, embedded in its structure. These charged elements enhance the clay’s ability to attract and exchange ions with surrounding substances. Ionic clay forms through weathering processes where minerals in rocks break down over time due to exposure to water, air, and other environmental factors. This process is particularly common in tropical regions. During this weathering, certain minerals release ions, and these ions become incorporated into the clay’s structure, giving it its characteristic ionic properties. The mineralogical content of ionic clays is then influenced by geological factors, such as parent rock types and weathering rates.
Ionic clays commonly host REEs due to their specific mineralogical composition and ionic adsorption capacity. The structure of the ionic clay’s allows for it to selectively attract and retain REEs.
Ionic clays can be mined with low-cost open pit mining techniques and processed using simple technologies. This is summarized by Mr. Burega, “in an ionic clay deposit the REE’s reside on the outside of the clay minerals, which makes them easier to recover, as compared to a hard rock deposit where the rock needs to be broken and treated in order to liberate the REE’s”.
The strategic importance of ionic clay deposits, especially for REEs, has spurred exploration efforts to identify and assess new occurrences around the world. Brazil is well known for these types of deposits as there are large regions that feature the favorable climatic conditions for the tropical weathering processes that lead to the formation of ionic clays.
Ionic clay deposits are well understood in Brazil and it is emerging as a significant source of REEs contained in ionic clays. One of the largest, the Serra Verde ionic clay REE deposit, also located in Goiás State, is permitted and recently commenced operations with full production anticipated in 2024.
The PCH Project
Appia’s PCH Project covers 175.5 square kilometres and is located approximately 30 kilometres from the city of Iporá, the centre for a region that has significant mineral exploration and mining activity as well as the infrastructure to support the industry. Active mines in the area include operations by Dundee Precious Metals and Yamana Gold. In addition, Vale and Dundee Precious Metals hold mineral exploration concessions immediately adjacent to the PCH project.
It is hosted within the Tocantins Structural Province in the Brasília Fold Belt, more specifically, the Arenópolis Magmatic Arc. The source of the mineralization has been classified as an alkaline intrusive of the Fazenda Buriti Plutonic Complex that was highly anomalous in REEs and niobium that were then concentrated into the ionic clays that formed at surface.
Prior exploration on the PCH Project included stream sediment sampling, soil sampling, geophysical surveys, auger drilling, diamond drilling and trench sampling programs. These programs have identified REE mineralization across a significant portion of the property with the most advanced being a two square kilometre zone known as Target 4. These early results indicated to Appia management that Target 4 contains mineralization comparable to other ionic clay hosted REE deposits in Brazil and, in particular, the soon to be production Serra Verde deposit.
The total weighted average from Appia’s first 57 reverse circulation drill holes was 2,287 parts per million (or 0.23 percent) total rare earth oxides (‘TREO’).
The highlight hole from those first holes was PCH-RC-63, which averaged 27,189 parts per million (or 2.72 percent) TREO over 24 metres.
Appia is now tapping into a higher-grade portion of Target 4. The Southwest Zone, an area measuring 1,000 by 500 metres, is proving to be particularly rich in REE mineralization. 10 reverse circulation holes drilled in the southwest zone of Target 4 returned a total weighted average of 7,578 parts per million (or 0.76 percent) TREO. And, to add to the potential value of the Southwest Zone, the amount of MREOs ranges from 312.58 to 5,717.47 ppm with a notable concentration at the bottom of each hole.
The results reported to date are significant in that the average grades reported to date from Target 4 are measurably higher than the prevailing average grade of secondary style REE deposits. The relatively high assay values for praseodymium, neodymium, terbium and dysprosium, the most valuable magnetic REEs, bodes well for the potential economic development of the project.
The average grade of the initial results from the Southwest Zone, for example, are greater than the reported average grade of Bayan Obo deposit, which is located in China and is said to be the main world producer of LREEs. However, REE mineralization at Bayan Obo, which averages 6.0% TREO, is hosted predominately within bastnaesite and monazite, which require drilling and blasting to mine followed by more complicated extraction techniques – as compared to an ionic clay hosted REE deposit such as Target 4.
As a result of these extraordinary initial results, Appia continues to move quickly at the PCH project. The company has engaged SGS Geological Services to prepare a maiden mineral resource estimate on Target 4. SGS will have their hands full as Appia still has yet to release results from 85 reverse circulation drill holes, 128 auger holes and 1 diamond drill hole. This substantial database will be complied in the coming weeks and the resource is expected to be completed in the first quarter of 2024.
“Upon the receipt of our maiden resource estimate, our focus will soon change to detailed mineralogy and metallurgy,” stated Mr. Burega. “This deposit has the potential to be an easy to process and low-cost deposit that could be a game changer in the REE market place.”
As the mineralization is at surface, the stripping ratio of a potential mine would be negligible. Combine that with the fact that the mineralized clays would only require earth moving equipment and the projected economics of extracting the REEs is dramatically reduced.
“Global interest in the REE industry continues to intensify, and the PCH Project is delivering results that surpass our expectations,” stated Mr. Burega. And that is based on only one target so far as work performed to date by Appia has only concentrated on Target 4, however there is tremendous exploration potential throughout the rest of the PCH Project. Ongoing exploration could provide additional exploration targets that could significantly add value to the property.