Dr. Jamil Sader reports

MONUMENTAL MINERALS CORP. COMPLETES RECONNAISSANCE EXPLORATION PROGRAM AND DEFINES DRILL TARGETS AT THE JEMI HEAVY RARE EARTH ELEMENT PROJECT, MEXICO

Monumental Minerals Corp. has provided an update on exploration at the Jemi rare earth element (REE) project located in Coahuila, Mexico, about 40 kilometres south of the Texas, United States, border. Recent work has included mapping, lithogoechemistry, rock and stream sediment sampling.

A four-month exploration program was completed at Jemi from August, 2022, with the objective to reduce the search space from approximately 800 hectares, as defined by an airborne radiometric and magnetic survey (see press release dated May 3, 2022), to the delineation of discreet drill targets. The program, which focused on the Jemi dikes and Veladora North areas known to host peralkaline intrusion-related REE mineralization, consisted of detailed geological mapping, regional stream sediment sampling, ground radiometric geophysical surveys and lithogeochemical sampling.

To date, 37 whole-rock analytical results from rocks collected at the Jemi dikes area have been received while results for 269 samples from the Jemi dikes and Veladora North areas are pending. Of the 37 samples, 11 returned values greater than 0.15 per cent total rare earth oxide (TREO), including six samples that returned values greater than 0.23 per cent TREO and up to 0.43 per cent TREO (22KRP004).

Heavy rare earth oxide (HREO) values (including dysprosium (Dy) and terbium (Tb)) ranged between 1,614 parts per million (ppm) and 39 ppm in peralkaline pegmatites, averaging 447 ppm. Six samples exceeded 680 ppm, including three that exceeded 830 ppm.

Light rare earth oxides (LREO) values (including neodymium (Nd) and praseodymium (Pr)) returned values up to 0.26 per cent and 0.23 per cent, with values in trend with HREO concentrations suggesting similar REE-hosting phases in the peralkaline rock samples.

Dr. Jamil Sader, chief executive officer and director, comments: "Our exploration at the Jemi dikes area of the Jemi project has defined where Monumental will drill to delineate the rare earth-, tantalum- and niobium-bearing pegmatites. This program has derisked the geological complexity and provides us with the confidence needed before moving to the next stage, which is drilling. We anticipate the pending results of analytical work will define further drill targets at the Veladora North area."

Rock samples with the highest REE content are those that are classified as peralkaline (sodium plus potassium concentrations are greater than aluminum concentrations). In most hard-rock HREE ore deposit mineral systems, rocks must be peralkaline in order for the crystallization of HREE-bearing silicate minerals such as eudialyte to occur. Eudialyte is a highly complex sodium, calcium, iron/manganese, zirconium silicate mineral that can contain up to 10 per cent RE2O3 (rhenium oxide) (enriched in HREEs), and 12 per cent ZrO2 (zirconium dioxide). Geological mapping has confirmed that samples with the highest TREO and HREO values are from pegmatitic bodies. Three-dimensional airborne magnetics modelling shows that surface pegmatite bodies are spatially associated with a numerous larger magnetic anomalies at depth that may represent potential source intrusions. Specific drill locations will target these pegmatites.

In addition to being REE mineralized, samples are also mineralized with respect to tantalum (Ta) and niobium (Nb). Laboratory determination of these critical elements in all samples from the Jemi project return values to 534 ppm Ta2O5 (tantalum pentoxide) and greater than 3,576 ppm niobium pentoxide. Within the Jemi dykes area specifically, laboratory determinations return values in four pegmatite samples that are greater than 68 ppm Ta2O5 and 919 ppm Nb2O5, and one sample that returned values of 170 ppm Ta2O5 and 2,560 ppm Nb2O5. Concentrations of these elements meet the threshold to be considered potentially economically significant.

Rare Earth element applications

Because of their unusual physical and chemical properties, the REEs have diverse defence, energy, industrial and military technology applications. Demand for REEs is expected to outstrip supply until at least 2030 dominantly due the increase in demand for neomagnets for electric vehicles and other electric motors (such as wind turbines, water pumps). The four key REEs that represent 94 per cent of the REE market by value are neodymium, praseodymium, dysprosium and terbium, all of which are enriched at Jemi. Neodymium-iron-boron magnets, which are the strongest known type of magnets, are used when space and weight are restrictions are present. The addition of HREEs terbium or dysprosium to magnets can double their optimal operating temperature from 80 degrees C to 160 degrees C. In addition, dysprosium with praseodymium increases a magnet's coercivity (the resistance of a magnetic material to change in magnetization).

Methodology and quality assurance/quality control

The analytical work reported on herein was performed by ALS Canada Ltd. at Hermosillo, 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 sampling or other factors that could materially affect the accuracy of the results.

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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