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

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."

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.

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.

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.

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

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.

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SOURCE Monumental Minerals Corp.