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

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

News Release - Vancouver, British Columbia – September 1 , 2022: 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.

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.

Figure 1. Shallow 1.5 m brine sampling holes made with an auger.

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 201 9. 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.

Figure 1. Near surface brine sample locations and lithium concentrations at the Monumental Minerals Laguna Blanca Project.

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 o r 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.”

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.

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 bla nk 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 analyti cal 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 re view 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: [email protected]

Or

Email: [email protected]

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 equipme nt 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.