Montero completes 625.25 m drillhole at Elvira, logs pyrite-bearing alteration

Toronto, Ontario--(Newsfile Corp. - August 4, 2026) - Montero Mining and Exploration Ltd. (TSXV: MON) (OTC Pink: MXTRF) (FSE: ES0) (" Montero " or the " Company ") is pleased to provide an update on geological logging and sampling of drillhole MON-ELV-02 at the Elvira Gold Project in northern Chile.

Drillhole MON-ELV-02, the replacement drillhole for the originally designated MON-ELV-01, was completed to a final depth of 625.25 metres. The hole tested a high-priority integrated target, defined through geological, geochemical, and geophysical interpretation, including geochemical vectoring, three-dimensional modelling, and artificial intelligence and machine-learning-assisted data integration.

Detailed geological logging indicates that the hole intersected strongly altered volcanic rocks overlying a feldspar-quartz-amphibole porphyry, together with pyrite-bearing high-sulphidation alteration. Assay results are pending and will be reported once received, reviewed, and verified.

Geological Logging Highlights

Intersected strongly advanced-argillic-altered lithic tuff from surface to approximately 194.40 metres.

Intersected a feldspar-quartz-amphibole porphyry from approximately 194.40 metres to the end of the hole; with hydrothermal alteration .

Identified an interpreted faulted contact between the volcanic sequence and the underlying porphyry at approximately 194.40 metres.

Intersected widespread quartz-alunite-pyrite alteration, extending through much of the porphyry.

Identified the base of oxidation at approximately 253 metres, below which sulphides are better preserved.

Observed pyrite-bearing sulphide mineralisation at multiple depths below approximately 253 metres and at the end of the hole, with pyrite occurring as disseminations, aggregates, stringers, and veinlets.

Encountered local vuggy silica, quartz-pyrite and chalcedony-pyrite veinlets, chalcedonic veins, hydrothermal crackle breccias and local cavities.

Identified chlorite-illite alteration between approximately 415-437 metres and 488-490 metres, with locally developed irregular pyrite veinlets.

Observed trace chalcopyrite and other possible sulphide phases that require laboratory confirmation.

The porphyry interval extends to more than 430 metres downhole. Visual logging records disseminated pyrite, locally accompanied by pyrite aggregates and thin sulphide-bearing veinlets. These observations are visual and preliminary; laboratory assays are required to determine whether gold, silver, copper, or other metals are associated with the sulphide system. The simplified geological log and chargeability relationship are shown in Figure 1.

Dr. Tony Harwood, President and Chief Executive Officer of Montero, commented: "Geological logging of drillhole MON-ELV-02 has supported important elements of our high-priority target model at Elvira. The hole intersected the predicted volcanic sequence and underlying porphyry, together with high-sulphidation alteration and pyrite corresponding spatially to the high-chargeability anomaly. Pyrite-bearing sulphide mineralisation and associated veining were observed at multiple depths below approximately 253 metres and at the end of the hole at 625.25 metres. Assay results will determine the metal content of the hydrothermal system."

Figure 1: Simplified geological log of drillhole MON-ELV-02 showing lithology, alteration, structure and the relationship with the modelled IP chargeability response. The hole intersected dacitic lithic-crystal tuff to approximately 194.40 metres, followed by feldspar-quartz-amphibole porphyry to the final depth of 625.25 metres. Quartz-alunite-pyrite alteration extends through much of the porphyry, and pyrite was observed at multiple depths below the base of oxidation which occurs at approximately 253 metres. The light-pink zone represents modelled chargeability of approximately 9.8-22.5 mV/V, while the dark-pink zone represents modelled chargeability greater than approximately 22.5 mV/V. Mineral identification is based on visual geological logging. Laboratory assays are required to determine the associated metal content.

To view an enhanced version of this graphic, please visit: https://images.newsfilecorp.com/files/11789/307920_b852f6e31474e90d_001full.jpg

Historical Drilling Context

MON-ELV-02 was drilled adjacent to historical drillhole EL-12, which was completed to a comparatively shallow final depth of approximately 281.85 metres. Buena Vista Gold Corp. reported that EL-12 intersected 4 metres grading 4.9 g/t Au from 264-268 metres, including 1 metre grading 17.85 g/t Au, close to the bottom of the hole. MON-ELV-02 extended the geological test by more than 340 metres below EL-12. Pyrite-bearing sulphide mineralisation with associated veining was observed at the end of MON-ELV-02 at 625.25 metres. Assays from MON-ELV-02 remain pending.

The historical results represent downhole lengths, and true widths are unknown. The historical collar location, drill orientation, sampling intervals, analytical methods and QA/QC procedures have not been verified by the Qualified Person. The Qualified Person has not completed sufficient work to verify the historical results because complete supporting sampling, analytical and QA/QC records are not currently available to Montero. The historical information is considered relevant because EL-12 is located adjacent to MON-ELV-02 and is provided solely as exploration context. It should not be treated as current exploration results or as a Mineral Resource or Mineral Reserve.

Integrated Geological, Geochemical and Geophysical Interpretation

Geological logging identified pyrite-bearing sulphide mineralisation within the porphyry in the area of the modelled IP chargeability anomaly. Pyrite was observed at multiple depths below the base of oxidation at approximately 253 metres and at the end of the hole, providing geological support for Montero's integrated targeting model.

The target was developed by combining geological mapping, historical drilling, alteration and structural interpretation, surface geochemistry, IP chargeability and resistivity, geochemical vectoring, and three-dimensional geological modelling. AI and machine-learning tools were used to assist in evaluating relationships between these datasets and prioritising targets for the 2026 drill programme.

Preliminary interpretation indicates that the feldspar-quartz-amphibole porphyry was overprinted by high-sulphidation hydrothermal alteration. Quartz-alunite-pyrite alteration, local vuggy silica and observed sulphides indicate that hydrothermal fluids penetrated deeply into the intrusive host. Representative drill core from 348.30 metres is shown in Figure 2. The relative timing of porphyry emplacement and the hydrothermal event remains interpretive. It remains uncertain whether the intersected porphyry was the source of the hydrothermal fluids or whether a separate, deeper mineralising intrusion is present. If the intersected porphyry was the source, the vertical overlap of porphyry-related and high-sulphidation alteration may indicate a telescoped hydrothermal system.

Figure 2: MON-ELV-02 drill core at 348.30 metres showing pyrite vein with white alunite and barite, hosted by feldspar-quartz-amphibole porphyry with a grey silica and quartz-alunite alteration halo. Mineral identification is based on visual logging, and metal content remains subject to laboratory confirmation.

To view an enhanced version of this graphic, please visit: https://images.newsfilecorp.com/files/11789/307920_montero2.jpg

Sampling, QA/QC and Chain of Custody

Drill core is managed under Montero's documented core handling, logging, sampling, and dispatch procedures and under the supervision of the Qualified Person. Core is placed sequentially in labelled trays at the drill rig, checked against driller depth and recovery records, and transported by authorised personnel to a secure core facility. Core movements are documented by hole number, box number, depth interval, date, transporter, and recipient.

At the core facility, the core is checked, reconstructed where appropriate, geologically, and geotechnically logged, and photographed before sampling. Sample intervals are selected and marked by the responsible geologist, with major geological contacts respected where practical. Core is cut with a diamond saw, and one consistent half is placed in a uniquely numbered sample bag; the remaining half is retained in the original tray for reference and potential check sampling.

Certified reference materials, blanks, and duplicate samples are inserted into the sample stream at frequencies approved by the Qualified Person. Sample bags are sealed and placed in numbered transport sacks with tamper-evident closures. Dispatch records identify the sample and sack numbers, seal numbers, releasing person, transporter, receiving laboratory, and laboratory acknowledgement. Samples are transported directly to the designated independent laboratory. QA/QC results will be reviewed by the Qualified Person before assay results are publicly reported or relied upon for technical interpretation.

The Company is not reporting analytical results in this release. Details of the analytical methods, laboratory accreditation and assay QA/QC performance will be disclosed when assay results are reported. Samples have been submitted to Andes Analytical Assay SpA in Copiapó, Chile, an independent laboratory. Details of the analytical methods and the accreditation applicable to those methods will be disclosed when assay results are reported.

Next Steps

Geological logging of MON-ELV-02 is complete. Core cutting and sample dispatch are continuing. Laboratory results will be used to assess:

Whether gold, silver, copper, or other metals are associated with the intervals in which pyrite-bearing sulphide mineralisation was observed.

The significance and distribution of the alteration and sulphide system.

The relationship between the intersected porphyry and any deeper mineralising source.

The geological information from MON-ELV-02 will be incorporated into Montero's three-dimensional geological model, together with the geochemical, geophysical, and structural datasets, to refine subsequent drill targeting. The model will continue to be updated as portable XRF screening, and laboratory assay results become available. Portable XRF readings are used solely as a geological screening tool and are not a substitute for laboratory assay results.

Caution Regarding Visual Observations

The geological observations reported in this release are preliminary and are based on visual examination of drill core. Visual identification of alteration, sulphides and mineralogy is inherently uncertain and should not be considered a substitute for laboratory assay results. The presence of pyrite, alteration or other sulphide minerals does not necessarily indicate economically significant gold, silver, or copper mineralisation. Assay results will be reported once received, reviewed, and verified by the Company.

Qualified Person

The scientific and technical information contained in this news release has been reviewed and approved by Mr. Marcial Vergara, B.Sc., an independent consulting geologist and a Qualified Person as defined by National Instrument 43-101 - Standards of Disclosure for Mineral Projects. Mr. Vergara is independent of the Company. Mr. Vergara verified the scientific and technical information disclosed in this news release through review of the drill core, geological logs, core photographs, drill records, sampling records, and relevant geological and geophysical data. No limitations were imposed on his verification of the current drilling information disclosed in this release.

About Montero

Montero Mining and Exploration Ltd. is a Canadian exploration company focused on gold and copper exploration in Chile. Montero holds a 100% interest in the Avispa copper-molybdenum project in the Palaeocene Porphyry Cu-Mo Belt of northern Chile and has an option to acquire the Elvira and Potrero gold projects in the Maricunga Gold Belt. These projects are being advanced through ongoing exploration activities.

Montero is listed on the TSX Venture Exchange under the symbol MON and has 8,453,833 common shares and 735,383 stock options outstanding.

For more information, contact: Montero Mining and Exploration Ltd. Dr. Tony Harwood, President and Chief Executive Officer Email: ir@monteromining.com Tel: +1 604 428 7050 www.monteromining.com

Neither 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 release.

Cautionary Statement Regarding Forward-Looking Information

This news release contains forward-looking information within the meaning of applicable Canadian securities laws. Forward-looking information includes statements regarding the interpretation of geological observations; the potential relationship between alteration, sulphide mineralisation and metal content; the timing, receipt and reporting of assay results; the refinement of the geological model; the application of geochemical vectoring, artificial intelligence and machine-learning tools to the integration and interpretation of exploration data; the design, sequence and timing of subsequent drillholes; and the continuation of the 2026 Elvira drilling programme.

Forward-looking information is based on assumptions and estimates considered reasonable by management as of the date of this release, including assumptions that laboratory analysis will be completed within anticipated timeframes; that assay results and additional geological information can be incorporated into the Company's geological model; that the Company will have sufficient personnel, equipment, funding and access to continue the drilling programme; and that required permits and regulatory approvals will remain in place.

Forward-looking information is subject to known and unknown risks, uncertainties and other factors that may cause actual results to differ materially from those expressed or implied. These risks include the speculative nature of mineral exploration; uncertainty in the interpretation of geological, geochemical and geophysical data; the possibility that laboratory results may not confirm visual observations or current geological interpretations; limitations and uncertainties associated with geochemical vectoring, artificial intelligence and machine-learning-assisted interpretation; delays in laboratory processing or receipt of assay results; operational and technical difficulties; adverse weather and site-access conditions; permitting and regulatory risks; commodity-price fluctuations; availability of financing; and other risks described in the Company's public disclosure documents filed on SEDAR+.

Readers are cautioned not to place undue reliance on forward-looking information. Montero undertakes no obligation to update forward-looking information except as required by applicable securities laws.

To view the source version of this press release, please visit https://www.newsfilecorp.com/release/307920

Newsfile Corp.

August 4, 2026 - 8:29 AM PDT

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