Monumental Minerals Provides Final Results Of Maiden Drilling Program At The Jemi Heavy Rare Earth Element Project, Mexico

VANCOUVER, Oct. 4, 2023 - Monumental Minerals Corp. ("Monumental" or the "Company") (TSX-V: MNRL) (FSE: BE5) (OTCQB: MNMRF) announces 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 (see Company's news release dated July 12, 2023). The program concluded on August 18, 2023 with a total of 2000 metres (m) drilled in 14 holes which ranged from 50 to 321 m in length.

Of the 2000 m drilled, 186 m of core (124 samples) returned anomalous REE concentrations. These samples contained total rare earth oxides (TREO¹) 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 (HREO²) 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 TREO¹ and HREO² values were observed in every drill hole except JV-23-08 and JV-23-10 (Figure 1, and Table 1).

Table 1. Jemi REE Project - La Veladora significant assay results.

Core logging confirmed anomalous REE assay values relate to the presence of the mineral eudialyte, consistent with surface mapping at the Jemi project (see Company's news release dated April 4, 2023). At Veladora North eudialyte was almost always found within discreet veins, dykes and sills, emplaced into host sedimentary rock sequences (Figure 2).

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 (Figure 3). 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, CEO 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 3D 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 3D aeromagnetic geophysical data (see 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 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 (see 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), 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).

The analytical work reported on herein was performed by ALS Canada Ltd. (ALS) at Zacatecas, Mexico (sample preparation) and Vancouver, B.C. (ICP-MS fusion). ALS is an ISO-IEC 17025:2017 and ISO 9001:2015 accredited geoanalytical laboratory and is independent of Monumental Minerals and the QP. Rock samples were subject to crushing at a minimum of 70% passing 2 mm, followed by pulverizing of a 250-gram split to 85% passing 75 microns. A 0.1-gram sample pulp was then subject to multi-element 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.

The scientific and technical information contained in this news release has been reviewed and approved by Kristopher J. Raffle, P.Geo. (BC) Principal and Consultant of APEX Geoscience Ltd. of Edmonton, AB, 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 includes a review of the sampling, analytical and test data underlying the information and opinions contained therein.

Monumental Minerals Corp. 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, USA border which the Company has an option to acquire 100% of the 3,650-hectare project. The Company has an option to acquire a 75% interest and title to the Laguna cesium-lithium brine project located in Chile and a 50.01% interest in the Salar De Turi lithium project in Chile.

On behalf of the Board of Directors,

/s/ "Jamil Sader"
Jamil Sader, Chief Executive Officer and Director

Contact Information:

Email: jsader@monumentalminerals.com

Or

Max Sali, VP Corporate Development and Director
Email: msali@monumentalminerals.com

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This news release contains "forward-looking information or statements" within the meaning of applicable securities laws, which may include, without limitation, the potential plans for the Company's projects, other statements relating to the technical, financial and business prospects of the Company, its projects and other matters. All statements in this news release, other than statements of historical facts, that address events or developments that the Company expects to occur, are forward-looking statements. Although the Company believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results may differ materially from those in the forward-looking statements. Such statements are based on numerous assumptions regarding present and future business strategies and the environment in which the Company will operate in the future, including the price of metals, the ability to achieve its goals, that general business and economic conditions will not change in a material adverse manner and that financing will be available if and when needed and on reasonable terms. Such forward-looking information reflects the Company's views with respect to future events and is subject to risks, uncertainties and assumptions, including the risks and uncertainties relating to the interpretation of exploration results, risks related to the inherent uncertainty of exploration and cost estimates and the potential for unexpected costs and expenses and those other risks filed under the Company's profile on SEDAR at www.sedarplus.ca. While such estimates and assumptions are considered reasonable by the management of the Company, they are inherently subject to significant business, economic, competitive and regulatory uncertainties and risks. Factors that could cause actual results to differ materially from those in forward looking statements include, but are not limited to, continued availability of capital and financing and general economic, market or business conditions, failure to secure personnel and equipment for work programs, adverse weather and climate conditions, risks relating to unanticipated operational difficulties (including failure of equipment or processes to operate in accordance with specifications or expectations, cost escalation, unavailability of materials and equipment, government action or delays in the receipt of government approvals, industrial disturbances or other job action, and unanticipated events related to health, safety and environmental matters), risks relating to inaccurate geological assumptions, failure to maintain all necessary government permits, approvals and authorizations, failure to obtain surface access agreements or understandings from local communities, land owners or Indigenous groups, fluctuation in exchange rates, the impact of Covid-19 or other viruses and diseases on the Company's ability to operate, an inability to predict and counteract the effects of COVID-19 on the business of the Company, including but not limited to, the effects of COVID-19 on the price of commodities, capital market conditions, restriction on labour and international travel and supply chains, decrease in the price of rare earth elements, lithium, cesium and other metals, loss of key employees, consultants, or directors, failure to maintain community acceptance (including from the Indigenous communities), increase in costs, litigation, and failure of counterparties to perform their contractual obligations. The Company does not undertake to update forward-looking statements or forward-looking information, except as required by law.

SOURCE Monumental Minerals Corp.