MONUMENTAL MINERALS SAMPLES 405 MG/L LITHIUM IN SHALLOW BRINE WITH A LITHIUM TO MAGNESIUM RATIO OF 2.5 AT THE LAGUNA BLANCA PROJECT, II REGION, CHILE

HIGH GRADE LITHIUM RESULT ACHIEVED DESPITE RECENT PRECIPITATION

VANCOUVER, BC, Sept. 1, 2022 /CNW/ - Monumental Minerals Corp. ("Monumental" or the "Company") (TSX-V: MNRL) (FSE: BE5) (OTCQB: MNMRF) is pleased to announce the results of a follow-up shallow brine sampling program at the Laguna Blanca lithium (Li) brine and cesium (Cs) sediment project (the "Project"), located within the Lithium Triangle, northern Chile.

Figure 1. Shallow 1.5 m brine sampling holes made with an auger. (CNW Group/Monumental Minerals Corp.)

Figure 1. Near surface brine sample locations and lithium concentrations at the Monumental Minerals Laguna Blanca Project. (CNW Group/Monumental Minerals Corp.)

Figure 2. The Li/Mg ratio vs Li concentration of Laguna Blanca brines demonstrates both favourable grades and processing chemistry. The ratio of Li/Mg is significantly better than other lithium brines from the Lithium Triangle. Figure is modified from Steinmetz et al. 2020. Abbreviations are as follows: AN = Antofalla Botijuelas, AR = Arizaro, CE = Centenario, DI = Diablillos, HM = Hombre Muerto, IN = Incahuasi, PC = Pocitos-Quirón, PG = Pastos Grandes, PZ = Pozuelos, RA = Ratones, RG = Río Grande, and RI = Rincón, CA = Cauchari, GG = Guayatayoc, JA = Jama, OL = Olaroz, and SG = Salinas Grandes, ATA = Atacama, and UYU = Uyuni . (CNW Group/Monumental Minerals Corp.)

The Laguna Blanca Project lies within the eastern Andean Geomorphic Belt of Chile's Central Andean Altiplano and is located 120 km from the Salar de Atacama, the largest lithium producing salar in the world. The felsic volcanic rocks of the Central Andean Altiplano are enriched in Li and Cs.

Monumental contracted Atacama Water SpA ("AW") to undertake a surface brine sampling campaign at the Company's Laguna Blanca Project between June 28 and July 6 (Photo 1). Sediment samples were also collected, results from which are pending. The objective of the program was to confirm results of previous sampling campaigns carried out by Lithium Chile Inc.

Seven shallow auger holes were completed by Monumental at sites proximal to the Laguna Blanca brine pool, where the groundwater table was deemed close enough to surface to obtain a brine sample. One brine sample was also collected from the surface. Analysis of the 4 sample locations that contained brine (three auger holes and the surface sample) returned lithium values to 405 milligrams per litre (mg/l), with mean and median values of 306 mg/l and 297 mg/l, respectively (Figure 1). These lithium values are consistent with shallow auger samples previously collected by Lithium Chile in 2019. The favorable lithium results, plus highly conductive TEM geophysical features deeper in the subsurface (see Monumental Minerals press release dated June 29, 2022), justify a deeper exploration drilling program.

Significantly, the ratios of lithium to magnesium ("Mg") within the Laguna Blanca brine samples range from 2.5 to 1.8 and are considerably higher than other known projects in Lithium Triangle (Figure 2). Besides Li grades, higher ratios of Li:Mg ratios are more favorable for brine-type developments of LCE, as the geochemical behavior of Mg ions can interfere with the Li purification process. Thus, low magnesium brines are considered more desirable. While the Laguna Blanca Salar samples were collected from near surface brines and may not be directly comparable to deeper subsurface brine chemistry or advanced projects or producing mines, the results are nonetheless encouraging.

Dr. Jamil Sader, CEO and Director of Monumental, comments:

"The brine results from Laguna Blanca are extremely encouraging. Although the samples were collected during the wet time of the year, and only 2 weeks after a major snow event, lithium concentrations are consistent with previous values determined by Lithium Chile in 2019. We are optimistic that our future drilling results will demonstrate lithium brine concentrations that significantly exceed these surface values. Additionally, we are excited about the low magnesium concentrations, as high values can be deleterious for processing."

Methodology and QA/QC

A total of 7 sample collection holes were drilled using a gasoline-powered auger to approximately 1.6 m depth. The holes were temporarily completed with 2 m length, 2-inch diameter PVC blank and screened casing. Sampling was conducted 48 hours after installation to let water levels equilibrate. Of the 7 auger holes, 4 did not reach the water table, thus a brine sample could not be obtained. One brine sample was collected from surface. Brine samples were taken by AW personnel using dedicated plastic bailers and collected in new, rinsed, one-litre plastic bottles. The bottles were sealed and labelled with the sampling site, date, and time. All samples were stored in coolers. Field parameters (pH, electrical conductivity, temperature, and density) were measured at each sample site. QA/QC protocols included the collection field duplicates and insertion of blank samples into the sample sequence. Following the completion of auger sampling casings were removed, and holes were back-filled to conform with the Company ESG policy on minimizing environmental impacts.

Brine samples were submitted to the laboratory of the University of Antofagasta for chemical analysis. The University of Antofagasta laboratory is independent of Monumental Minerals and the QP. The laboratory of the University of Antofagasta is not ISO certified, but it is specialized in the chemical analysis of brines and inorganic salts, and their laboratory quality control and analytical procedures are of high quality and are appropriate with respect to the sample media. The analytical methods used were inductively coupled plasma optical emission spectroscopy for cations, ion selective electrodes for anions, and titration for carbonate and bicarbonate determinations.

Qualified Person

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 cautions that past results or discoveries on proximate land are not necessarily indicative of the results that may be achieved on the Laguna Blanca Project.

About Monumental Minerals Corp.

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 Blanca project located 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
Email: msali@monumentalminerals.com

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this news release.

References
Steinmetz, R.L.L., Salvi, S., Sarchi, C., Santamans, C. and Steinmetz, L.C.L., 2020. Lithium and brine geochemistry in the salars of the Southern Puna, Andean plateau of Argentina. Economic Geology, 115(5), pp.1079-1096.

Forward Looking Information

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, the timing, completion and expected outcomes of the next phase of exploration work on the Laguna Project, 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.sedar.com. 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.