Announcement • May 21
GR Silver Mining Ltd Reports Best Ever Drill Results At San Marcial GR Silver Mining Ltd. announced outstanding drill results from hole SMS26-04 in the SE Area of San Marcial. SMS26-04 intersected two well-defined mineralized zones located at the upper and lower contacts of the chlorite–hematite-rich breccias, associated with stockwork zones and andesitic to dioritic dykes emplaced along multiple structural intersections. High-grade silver mineralization is developed within the chlorite–hematite-rich breccias at the contact between the upper Oligocene volcanic sequence and the lower Jurassic volcano-sedimentary units. The exceptional silver grades encountered in SMS26-04 highlight the strong structural control of the mineralizing system and further support the exploration potential of key inflection zones, including structural jogs and shear zones, as priority targets for additional high-grade mineralization. SMS26-04 intersected 45.1 m true width at 1,623 g/t Ag, from 267.85 m down hole, including 18.85 m true width at 3,846 g/t Ag with 0.7% Pb and 2.5% Zn, and including 8.25 m true width at 8,579 g/t Ag with 1.6% Pb and 5.5% Zn. SMS26-04 also intersected 20.6 m true width at 32 g/t Ag from 328.60 m down hole, including 7.1 m at 51 g/t Ag and 0.15 g/t Au. High-grade silver mineralization in SMS26-04 consists of multi-stage hydrothermal breccias, subsequently overprinted by polymetallic silver-lead-zinc events. These mineralizing events are spatially associated with the intersection of E-W, N-S, and NE-SW structural trends, which generate high-grade shoots and provide a key exploration vector for targeting additional high-grade mineralized intersections within the San Marcial breccia-hosted body. SMS26-04 confirms the continuity of high-grade silver mineralization within the chlorite–hematite hydrothermal breccias and supports the interpretation of a boiling zone developed between 700 and 300 metres elevation above sea level, plunging toward the southeast. In SMS26-04, the calcite boiling level is characterized by overprinting mineralization consisting of acanthite, argentite, and abundant native silver, together with galena and brown sphalerite, indicating low to intermediate-temperature precipitation conditions. Comparison of SMS26-04 with SMS25-11 further demonstrates that structural controls play a significant role in the distribution of high-grade silver mineralization. Sub-horizontal flexures within the breccia create zones of reduced permeability for epithermal fluids, whereas subvertical sections enhance fluid migration and mineral deposition. These sigmoidal structural geometries generate high-grade ore shoots at the intersection of E-W, N-S, and NE-SW structural trends. Drill hole SMS26-04 was specifically designed to test one of these structural inflection zones and has successfully validated the dilatational jog and structural intersection model. Regional studies in the Sierra Madre Occidental indicate that the San Marcial breccia structure originated as a reverse fault during a transition from compressional to extensional tectonics and was later reactivated as a normal fault during Early Oligocene. The breccia geometry, particularly the thicker shallow-dipping sections, supports this interpretation of high-grade silver mineralization appears to be concentrated in structural flexure zones where the strike of the breccia changes from NW to E-W, suggesting that these zones acted as favorable pathways for hydrothermal fluid flow and mineral deposition. Drill holes close to surface like SMS22-22 and SMS22-16 support this structural model and represent an open shear zone with stockwork in between main breccia zones with continuous silver mineralization and local high-grade zones. The outstanding results of SMS26-04 highlight the exploration potential between the Central Area and SE Extension and confirm the potential for resource growth. The plunge orientation that connects SMS26-04 with other strong drill hole results in the area, such as SMS25-09 with 75.2 m at 260 g/t Ag and SMS22-10 with 101.6 m at 308 g/t, defines a high-grade structural corridor and a high priority exploration target. 
