Dr. Jamil Sader reports

MONUMENTAL MINERALS PROVIDES FINAL RESULTS OF MAIDEN DRILLING PROGRAM AT THE JEMI HEAVY RARE EARTH ELEMENT PROJECT, MEXICO

Monumental Minerals Corp. has released results from the maiden drilling program at the Jemi rare earth element (REE) project in Coahuila, Mexico, about 40 kilometres south of the Texas, United States, 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 dikes and sills at the surface. In addition, 3-D aeromagnetic highs at less than 300 metres (m) depth were targeted, interpreted to be the magmatic bodies that fed veins, dikes and sills observed at surface (see the company's news release dated July 12, 2023). The program concluded on Aug. 18, 2023, with a total of 2,000 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 2,018 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 (see the company's news release dated April 4, 2023). At Veladora North, eudialyte was almost always found within discrete veins, dikes 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.

Dr. Jamil Sader, chief executive officer and director, comments:

"The Monumental Minerals drilling program at Jemi was the first in the area, with all drill holes targeting prospective areas based on surface geochemistry and 3-D aeromagnetic geophysics. Interpretation of drilling results including assays and core logging show that Jemi continues to be a highly prospective target for rare earth elements. Our initial drilling campaign has proven very valuable in vectoring toward potential buried mineralization at Jemi."

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 3-D aeromagnetic geophysical data (see the company's news release dated April 4, 2023), 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 dikes area.

The Jemi project is characterized by broad areas of peralkaline intrusion-related REE mineralized dikes and sills at the margins of the La Vasca igneous complex observed at that surface (see the company's news release dated April 4, 2023). These intrusive bodies contain high grades of heavy rare earth oxides (HREO) dysprosium (Dy) and terbium (Tb), and light rare earth elements (LREE) neodymium (Nd) and praseodymium (Pr), all critical to permanent magnets for electric vehicles. Additionally, surface samples contain high concentrations of niobium (Nb) and tantalum (Ta).

Methodology and quality assurance/quality control

The analytical work reported on herein was performed by ALS Canada Ltd. at Zacatecas, Mexico (sample preparation), and Vancouver, B.C. (inductively coupled plasma mass spectrometry fusion). ALS is an ISO-IEC 17025:2017 and ISO 9001:2015 accredited geoanalytical laboratory and is independent of Monumental Minerals and the qualified person. Rock samples were subject to crushing at a minimum of 70 per cent passing two millimetres, followed by pulverizing of a 250-gram split to 85 per cent passing 75 microns. A 0.1-gram sample pulp was then subject to multielement ICP-MS analysis via lithium-borate fusion to determine individual REE content (ME-MS81). Monumental Minerals' quality assurance/quality control (QA/QC) program for field rock samples includes the insertion of certified reference standards into the sample sequence to confirm the accuracy of the reported results. Monumental Minerals detected no significant QA/QC issues during review of the data, and is not aware of any drilling, sampling or other factors that could materially affect the accuracy or reliability of the data referred to herein.

Qualified person

The scientific and technical information contained in this news release has been reviewed and approved by Kristopher J. Raffle, PGeo (British Columbia), principal and consultant of Apex Geoscience Ltd. of Edmonton, Alta., a director of the company, and a qualified person as defined in National Instrument 43-101 -- Standards of Disclosure for Mineral Projects. Mr. Raffle verified the data disclosed which include a review of the sampling, analytical and test data underlying the information and opinions contained therein.

About Monumental Minerals Corp.

Monumental Minerals is a mineral exploration company focused on the acquisition, exploration and development of mineral resource properties in the critical and electric metals sector. The company's flagship asset is the Jemi HREE project located in Coahuila, Mexico, near the Texas, U.S., border which the company has an option to acquire 100 per cent of the 3,650-hectare project. The company has an option to acquire a 75-per-cent interest and title to the Laguna cesium-lithium brine project located in Chile and a 50.01-per-cent interest in the Salar De Turi lithium project in Chile.

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