Monumental Minerals Corp. announced results from the maiden drilling program at the Jemi rare earth element (REE) project (the "Project") in Coahuila, Mexico, about 40 km south of the Texas, USA border. One diamond drill rig commenced drilling on the Veladora North and South prospect areas in early July to test areas with a high frequency of REE-mineralized dykes and sills at the surface.

In addition, 3D aeromagnetic highs at less than 300 m depth were targeted, interpreted to be the magmatic bodies that fed veins, dykes and sills observed at surface. The program concluded on August 18, 2023 with a total of 2,000 metres (m) drilled in 14 holes which ranged from 50 to 321 m in length. Of the 2,000 m drilled, 186 m of core (124 samples) returned anomalous REE concentrations.

These samples contained total rare earth oxides (TREO) results greater than 500 parts per million (ppm), with a maximum of 2018 ppm, and a mean and standard deviation of 717 and 282 ppm (respectively). Heavy rare earth oxides (HREO) are also highest in these samples with a maximum of 517 ppm, and a mean and standard deviation of 164 ppm and 98 ppm (respectively). Anomalous TREO and HREO values were observed in every drill hole except JV-23-08 and JV-23-10.

Core logging confirmed anomalous REE assay values relate to the presence of the mineral eudialyte, consistent with surface mapping at the Jemi project. At Veladora North eudialyte was almost always found within discreet veins, dykes and sills, emplaced into host sedimentary rock sequences.  At Veladora South, elevated REE values are regularly associated with massive pegmatitic syentite intrusions, especially within holes JV-23-11, JV-23-13, and JV-23-14. Eudialyte was commonly observed as intergrowth mineralization within these intrusions.

Drill hole intersections with anomalous REEs were generally continuous and associated with aegirine as banded lithologies. The geochemistry at Veladora South indicates that the peralkaline rocks are highly fractionated, a characteristic shared with major REE deposits. Veladora South is also associated with intense pervasive fentinization (metasomatic alteration by nepheline syenite intrusive rocks) of host sedimentary rocks resulting in skarn minerals throughout boreholes, supporting the existence a buried nepheline syenite intrusion.

The company used artificial intelligence (AI) to interpret the geochemistry of drill core and determined that the Veladora South area is more prospective. These data, plus core mineralogy, fentinization alteration in conjunction with 3D aeromagnetic geophysical data will be used to target other potential high-grade mineralization at Veladora South, and adjacent areas to the south of the current drill program within the untested Jemi Dykes area.   The Jemi project is characterized by broad areas of peralkaline intrusion-related REE mineralized dykes and sills at the margins of the La Vasca igneous complex observed at that surface.

These intrusive bodies contain high grades of heavy rare earth oxides (HREO) dysprosium (Dy) and terbium (Tb), light rare earth elements (LREE) neodymium (Nd) and praseodymium (Pr), all critical to permanent magnets for EVs. Additionally, surface samples contain high concentrations of niobium (Nb) and tantalum (Ta).