Ms. Mihaela Iancu of McEwen Mining reports

MCEWEN COPPER: LOS AZULES - LATEST ASSAY RESULTS

McEwen Copper Inc., 52 per cent owned by McEwen Mining Inc., has released additional copper values over wide intercepts resulting from drilling performed on its Los Azules project, located in San Juan, Argentina. McEwen Copper recently published an updated preliminary economic assessment (PEA) on a copper leaching phase of development (see release dated June 20, 2023). Infill and other resource drilling completed since the PEA model data cut-off date confirm very good alignment of new assay results to the resource model prediction for the same area. Also, copper grade continuity modelled in the core of the deposit is well supported by core logging and new assay results. Los Azules is a large copper-gold-silver porphyry deposit with growth potential, it has many features comparable with world-class copper-gold deposits in South America, and its depth and lateral extent have not yet been determined. Infill drilling serves several purposes: providing better data density to upgrade confidence in the mineral resources, providing material and data for metallurgical, geotechnical and hydrological studies.

Highlights:

• Hole AZ23220 intercepted an enriched zone of 398 metres (m) grading 0.75 per cent Cu (estimated true thickness) and includes a subinterval of 124 m grading 1.43 per cent Cu.
• Hole AZ23218 intercepted an enriched zone of 202 m grading 0.63 per cent Cu (estimated true thickness) contained within an overall intercept of 239.2 m grading 0.59 per cent Cu.
• Hole AZ23216 intercepted an enriched zone of 338 m grading 0.58 per cent Cu and primary mineralization of 84 m grading 0.27 per cent Cu.
• Hole AZ23206 intercepted 353 m of 0.46 per cent Cu, including an enriched zone intercept of 190 m grading 0.57 per cent Cu.

The latest drilling program, which began in October, 2022, was concluded on June 19, 2023. Up to 15 rigs completed approximately 39,900 m of drilling in 138 holes, to evaluate geotechnical, hydrological, resource and exploration-related parameters and opportunities. The Los Azules drill hole database now totals approximately 126,000 m.

To test the Cu percentage resource model veracity versus actual drilling results, 24 infill holes completed subsequent to the PEA model update were compared with expected results based on the model. The length-weighted average grade of the new drilling was 0.567 per cent Cu versus a resource model prediction of 0.520 per cent Cu. This limited test of the resource model's predictive capacity is very encouraging with actual grades being 9 per cent higher than the model prediction.

Preparations are under way for the next phase of drilling, anticipated to begin in early October. This phase will continue to increase geologic certainty with drilling needed to delineate a measured mineral resource estimate on the material expected to be mined in the first five years of operation, covering more than the payback period and other technical evaluations.

Description of results

Hole AZ23218 has been added to section 44 to infill a 300 m gap in drilling between holes AZ23189 and AZ22170. The hole returned a higher-grade enriched zone intercept than either of those holes with 202 m of 0.63 per cent Cu, including a subinterval of 20 m of 0.91 per cent Cu. Over all, the cross-section is characterized by a 200 m to 300 m flat-lying enriched zone buried immediately below a thin leached zone horizon. The mineralization in hole AZ23218 extends at depth into the Primary (or Hypogene) zone with an intercept of 37.2 m of 0.39 per cent Cu.

Hole AZ23220 returned outstanding enriched zone results of 398 m of 0.75 per cent Cu, including a subinterval of 124 m grading 1.43 per cent Cu which exceeds the base case grade of the recently released 2023 updated PEA for Los Azules by more than three times. The hole was positioned to test for a structural corridor located in the core of the deposit. The high grades returned occur within a hydrothermal magmatic breccia, which is representative of that corridor. The mineralization and lithology logged are consistent with the previously released neighbouring holes AZ22171 and AZ23201 which supports the company's view that continuity within the deposit is very good and in harmony with the resource model that has been developed.

Hole AZ23216 highlights a 338 m enriched zone intercept grading 0.58 per cent Cu, including a 48 m interval of 0.90 per cent Cu. The hole was positioned to extend mineralization east from hole AZ17133. The thick intercept occurred toward the eastern flank of the deposit, where normally both grade and thickness begin to diminish. Mineralization continues at depth where Primary mineralization corresponds to an 84 m interval of 0.27 per cent Cu.

Hole AZ23206 intersected 190 m of enriched zone mineralization grading 0.57 per cent Cu and includes a 94 m section of 0.62 per cent Cu. Mineralization continues at depth where the Primary zone was intersected with 163 m of 0.32 per cent Cu.

Technical information

The technical content of this press release has been reviewed and approved by Stephen McGibbon, PGeo, McEwen Mining's senior consulting geologist and a qualified person as defined by National Instrument 43-101.

All samples were collected in accordance with generally accepted industry standards. Drill core samples, usually taken at two m intervals, were split and submitted to the Alex Stewart International laboratory located in the province of Mendoza, Argentina, for the following assays: gold determination using fire fusion assay and an atomic absorption spectroscopy finish (Au4-30); a 39-multielement suite using inductively coupled plasma optical emission spectroscopy analysis (ICP-AR 39); copper content determination using a sequential copper analysis (Cu-Sequential LM-140). An additional 19-element analysis (ICP-ORE) was performed for samples with high sulphide content.

The company conducts a quality assurance/quality control program in accordance with NI 43-101 and industry best practices using a combination of standards and blanks on approximately one out of every 25 samples. Results are monitored as final certificates are received, and any reassay requests are sent back immediately. Pulp and preparation sample analyses are also performed as part of the QA/QC process. Approximately 5 per cent of the sample pulps are sent to a secondary laboratory for control purposes. In addition, the laboratory performs its own internal QA/QC checks, with results made available on certificates for company review.

About McEwen Mining Inc.

McEwen Mining is a gold and silver producer with operations in Nevada, Canada, Mexico and Argentina. In addition, it has significant exposure to copper through its 52-per-cent ownership of McEwen Copper. The company's goal is to improve the productivity and extend the life of its mines with the objective of increasing its share value and price and providing a yield. Rob McEwen, chairman and chief owner, has personal investment in the company of $220-million (U.S.). His annual salary is $1 (U.S.).

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