GR Silver Extends San Marcial's High-Grade System With 35.45 Meters at 311 g/t Silver

• A step-out hole in the Southeast Area returned 35.45 meters true width at 311 grams per tonne (g/t) silver, including 0.4 meters at 4,232 g/t silver and 1.35 meters at 996 g/t silver.
• The hole extends silver mineralization about 80 meters further down-dip, with vertical continuity of at least 300 meters in a system that remains open at depth.
• At the Parallel Breccia Target, a hole returned 2.15 meters true width at 1,164 g/t silver, 0.6% copper and 0.37% tungsten, which the company says may indicate a multiphase hydrothermal system potentially reflecting a transition toward a porphyry-related mineralizing environment.
• GR Silver has drilled 7,756 meters in 25 holes, with assays pending from 6 holes, and has shifted the program to test a high-grade dilation zone.
• Road upgrades in Durango are nearing completion, and the company is targeting a faster drilling pace and a mineral resource estimate update by mid-2027.

Company Overview

GR Silver Mining (TSXV: GRSL | OTCQX: GRSLF | FRA: GPE) is a Canadian-based, Mexico-focused mineral exploration company advancing silver-gold resource expansion on its 100%-owned assets on the eastern edge of the Rosario Mining District in southeast Sinaloa State, Mexico. The company controls 100% of the Plomosas Project, which includes the high-grade silver discovery at the San Marcial Area and the former Plomosas underground mine. Its advanced-stage exploration concessions cover 78 square kilometers.

Southeast Area Hole Extends the High-Grade System Down-Dip

GR Silver Mining reported a step-out hole in the Southeast (SE) Area at San Marcial that returned 35.45 meters true width at 311 grams per tonne (g/t) silver. The interval contains 4 higher-grade zones of hydrothermal breccia:

• 0.4 meters at 4,232 g/t silver
• 0.35 meters at 1,901 g/t silver
• 0.5 meters at 2,017 g/t silver
• 1.35 meters at 996 g/t silver

The hole shows silver mineralization continuing about 80 meters further down-dip, with vertical continuity of at least 300 meters. According to the company, the system plunges southeast and remains open at depth.

The highest-grade zone is chlorite-quartz-calcite breccia with acanthite, sphalerite and galena. The hole cut chlorite-hematite hydrothermal breccias across upper Oligocene volcanics and Jurassic volcano-sedimentary rocks, mainly along a structural contact. Dioritic dykes become more frequent toward the SE Extension and are linked to an Oligocene subvolcanic intrusive complex, and the company said the crosscutting relationships suggest the mineralization developed during a later hydrothermal event, after the intrusive complex was emplaced.

Parallel Breccia Target Returns 1,164 g/t Silver With Copper & Tungsten

The Parallel Breccia Target lies about 300 meters southwest of the 2023 NI 43-101 resource area. One hole there returned 2.15 meters true width at 1,164 g/t silver, 0.6% copper and 0.37% tungsten, from 104.80 to 107.00 meters downhole in hydrothermal breccia and stockwork. The same silver-copper-tungsten association was first recognized in a 2025 hole, which returned 9.0 meters at 374 g/t silver, 0.3% copper and 0.59% tungsten, including 1.0 meter at 1,542 g/t silver, 1.4% copper and 0.62% tungsten. Mineralization at the target is now traced over about 300 meters along strike and remains open in both directions.

The breccias are quartz-calcite-hematite-tourmaline units in the Lower Jurassic volcano-sedimentary sequence, cut by stockwork veinlets, and lie within a high-chargeability anomaly around a Cretaceous granodioritic intrusive complex. The company described multiple hydrothermal events, with tourmaline, actinolite, albite, and K-feldspar alteration, and said the silver-copper-tungsten association and alteration may indicate a multiphase hydrothermal system, potentially reflecting a transition toward a porphyry-related mineralizing environment.

Program Status & Drilling Pace

GR Silver has drilled 7,756 meters in 25 holes, with results received for 19 holes and assays pending for 6. The program has shifted to test the high-grade dilation zone extending from an earlier 2026 hole in the SE Area, which returned 45.1 meters true width at 1,623 g/t silver, including 8.25 meters at 8,579 g/t silver. Two other SE Area step-outs returned 11 g/t to 50 g/t silver over 6.9 to 9.7 meters of breccia and stockwork, and the company is developing its exploration model for that area.

Road upgrades in Durango are nearing completion as the wet season ends. President and Chief Executive Officer of GR Silver Mining, Eric Zaunscherb, tied the faster drilling pace to the road work and the mineral resource estimate (MRE) update targeted for mid-2027:

"As we emerge from this year's extensive wet season, our access road upgrade in Durango will allow us to accelerate our drill program, which should enable delivery of our planned MRE update by mid-2027."

Dr. Gilles Arseneau, P.Geo., of Arseneau Consulting Services Inc., a qualified person under NI 43-101, reviewed and approved the technical content. Samples were prepared and assayed at SGS de México in Durango, with blanks, duplicates, and standards inserted in every batch.

Next Steps

• Drill 2 more holes on the same SE Area section to test deeper continuity, potentially extending the system to 500 meters down-dip from surface.
• Report assays from the 6 holes with pending results.
• Drill deeper holes into the central intrusive body later in the program to test the potential porphyry model.
• Target the MRE update by mid-2027, building on the 2023 NI 43-101 resource estimate, where the company suggests some Inferred material could be upgraded to Indicated.

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