GR Silver Mining: Expanding the San Marcial Discovery While Restarting Permitted Plomosas Mine

• Major silver discovery at San Marcial delivers exceptional grades and widths, including 101m at 308 g/t Ag, with 80% of the geophysical anomaly still untested.
• Fully funded exploration provides 12–15 months of runway for an aggressive drilling program aimed at expanding the current 68 Moz San Marcial resource.
• Permitted historic mine at Plomosas offers near-term production potential, supported by 7.4 km of underground development, existing infrastructure, and active operating permits.
• High-grade zones identified through bulk sampling at Plomosas highlight 21 areas grading between 1,800 and 7,000 g/t silver equivalent.
• Multiple upcoming catalysts include a resource update and PEA in 2026, the start of bulk sample test mining early that year, and consistent drilling results expected throughout the program.

San Marcial Area: A Primary Silver Discovery with Massive Upside

GR Silver Mining's flagship discovery at San Marcial represents a rare find in Mexico's mining landscape. A predominantly silver deposit in a region typically known for polymetallic mineralization. CEO Marcio Fonseca emphasizes:

"San Marcial is predominantly silver - 85% - which is not very common in Mexico. Most of the deposits are polymetallic."

The discovery sits on the edge of a significant intrusive-related geophysical anomaly, of which only 20% has been tested to date. The company currently operates two drill rigs on site, with plans to increase the number in coming months as the program expands.

What makes this discovery particularly compelling is the continuity and grade of mineralization. After more than a year and a half of geological studies, the company has identified continuous mineralization from the discovery hole, with results showing "100 meters at 308 grams per tonne silver" stepping down approximately 300 meters to intersect "75 meters, or 260 grams per ton of silver."

The geological cross-section reveals wide hydrothermal breccias occurring at shallow depths, with multiple high-grade intersections including 44.5 meters at 156 g/t silver, and an exceptional 10,550 g/t silver intersection. This mineralization style - wide zones of silver-dominant material - positions San Marcial as a potential bulk-tonnage target with significant operational advantages.

Pitch Perfect Presentation, with Chief Executive Officer Marcio Fonseca

Resource Expansion: Doubling the Footprint at San Marcial

The current NI 43-101 resource at San Marcial stands at 68 million ounces of silver, but this represents only a fraction of the system's potential. Fonseca notes:

"This is a major discovery for the company because we are expanding the footprint of the mineralization. This means that in the upcoming resource, which is a major catalyst next year, this is going to be a much larger resource than what we have today."

The longitudinal section of the San Marcial resource area shows systematic step-out drilling successfully expanding the known mineralization. Recent drilling includes holes 11 and 12, which extend the mineralization concept established by hole 9's success. The CEO expects results "by mid-November" with "the hole 13 and probably one more hole before the year end."

This aggressive drilling approach targets at least a doubling of the mineralization footprint ahead of a resource update planned for mid-2026. With 80% of the geophysical anomaly still untested, the exploration upside remains substantial. The systematic approach o f using multidisciplinary research including geophysics, geology, and geochemistry to guide step-out drilling reduces risk while maximizing the potential for continued success.

Plomosas Historic Mine: Fast-Track to Production

While San Marcial represents long-term exploration upside, the Plomosas historic mine offers a near-term path to production with significantly reduced capital requirements. The mine operated until 2001 and retains substantial infrastructure including 7.4 kilometers of underground development, existing permits for 600 tons per day production, and year-round road access.

Fonseca explains the strategic importance:

"Having an asset like Plomosas mine, which is a historic mine that was shut down in 2001, with all the infrastructure there. The mine is built. The only thing that we don't have is a plant. And we have the permits to operate. It's very important for the company, particularly in this silver market."

The proximity of Plomosas to San Marcial is just five kilometers away. This creates potential synergies between the two operations. Material from San Marcial could potentially be processed through a pilot plant at Plomosas, creating operational efficiencies and reducing overall capital requirements for development.

Current bulk sampling and underground mapping have identified 21 accessible areas within the historic mine where previous operators left mineralization behind. These areas show "intervals of 2,000, 3,000, even 7,000 grams per tonne silver equivalent" which represents "a very attractive scenario for us as a way to look to capture value from this historic mine in the current silver price market."

Bulk Sample Test Mining: Validating High-Grade Zones

GR Silver's approach at Plomosas focuses on selective, high-grade mining rather than large-scale bulk tonnage. The company plans to start at 250 tons per day with potential to scale up to the permitted 600 tons per day capacity based on results.

The bulk sampling program has revealed numerous high-grade zones that weren't adequately captured in the 2023 resource estimation. Sample results from accessible underground areas include:

• 0.6m at 3,993 g/t AgEq (including 15.20 g/t Au)
• 1.2m at 1,870 g/t AgEq
• 0.8m at 1,192 g/t AgEq
• 2.2m at 3,163 g/t AgEq
• 0.8m at 2,019 g/t AgEq (including 5.74 g/t Au)

These grades demonstrate the selective, high-value nature of the mineralization remaining in the historic workings. Metallurgical test work is currently underway to confirm processing parameters, while engineering studies progress on the pilot plant design.

The bulk sample test mining program is targeting commencement in early 2026, representing a near-term catalyst that could generate cash flow while larger development studies continue. The existing underground infrastructure significantly reduces the capital required compared to a greenfield development scenario.

Value Creation Roadmap: Clear Catalysts Through 2026

GR Silver has laid out a transparent timeline of milestones and catalysts that provide multiple inflection points for value creation:

Completed Milestones:

• Phase 1 step-out drilling (3,000m) at San Marcial
• 46-hole permit granted for Phase 2 drilling (~15,000m)

Near-Term Catalysts (Q4 2025 - Q1 2026):

• Continued drilling results from San Marcial holes 11, 12, 13 and additional holes
• Bulk sample test mining commencement at Plomosas
• Advance permitting for San Marcial development

2026 Catalysts:

• Resource update and PEA for combined Plomosas Project
• Potential resource growth at San Marcial-Plomosas
• Phase 2 implementation of pilot plant at Plomosas
• Underground drilling from San Marcial tunnel

The company's track record demonstrates execution capability: 18,000 meters drilled resulting in the 68 million ounce silver equivalent resource at San Marcial. With the company "fully funded for the next 12 to 15 months," investors can expect consistent news flow as the drilling program advances and bulk sampling progresses.

The Investment Thesis for GR Silver Mining

• ‍Discovery Upside with Reduced Risk: The San Marcial discovery has demonstrated continuity and scale, with wide intersections of high-grade silver mineralization. With 80% of the geophysical anomaly untested, exploration upside remains substantial. The company's systematic, multidisciplinary approach to exploration reduces risk by using multiple datasets to guide drilling decisions.‍
• Near-Term Production Optionality: Unlike pure exploration plays, GR Silver has a permitted, infrastructure-rich historic mine that could generate cash flow in the near term. The bulk sample test mining approach allows the company to validate the economic potential of Plomosas with minimal capital investment while advancing toward commercial production. This dual-track approach—exploration at San Marcial and development at Plomosas—provides multiple pathways to value creation.‍
• Primary Silver Exposure: In a market where most Mexican deposits are polymetallic, San Marcial's 85% silver content provides direct leverage to silver prices. As industrial and investment demand for silver increases, primary silver deposits become increasingly valuable. The combination of high-grade, bulk-mineable deposits at shallow depths positions the project favorably on the cost curve.‍
• Infrastructure and Permitting Advantages: Significant value has already been created through the existing 7.4 kilometers of underground development at Plomosas and the operating permits already in place. These infrastructure advantages significantly reduce capital requirements and timeline to production compared to greenfield projects. The integration potential between San Marcial and Plomosas creates operational synergies that could further reduce development costs.‍
• Funded Growth: With 12-15 months of funding secured, the company can execute its drilling program without near-term dilution concerns. This funded position allows management to focus on execution and value creation through the drill bit rather than capital raising, a significant advantage in the junior mining sector.‍
• Experienced Management with Skin in the Game: The geological team's deep understanding of the deposit, demonstrated through successful step-out drilling, indicates strong technical capabilities. The systematic approach to exploration and the multiple-discipline integration suggests experienced management making data-driven decisions.‍
• Valuation Upside from Resource Growth: With the current resource at 134 million ounces silver equivalent (68 million at San Marcial) and clear potential to "at least two times the footprint" at San Marcial, a resource update in mid-2026 represents a significant catalyst. Resource growth coupled with advancing engineering studies toward production could materially re-rate the company's valuation.

The combination of exploration upside, near-term production potential, infrastructure advantages, and funded growth positions GR Silver Mining as a unique opportunity in the silver space, offering both the blue-sky potential of a discovery story and the de-risked path to production of a development company.

TL;DR

GR Silver Mining is advancing a significant silver discovery at San Marcial in Mexico, with wide, high-grade intersections including 101 meters at 308 g/t silver. The company has only drilled 20% of a major geophysical anomaly and is fully funded for 12-15 months of aggressive exploration. Simultaneously, GR Silver is developing the permitted Plomosas historic mine through bulk sampling, targeting high-grade zones with grades reaching several thousand g/t silver equivalent. With 134 million ounces of silver equivalent resources, existing infrastructure at Plomosas, and a clear path to near-term production, the company offers investors exposure to primary silver mineralization in a favorable jurisdiction with multiple catalysts ahead.

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