GR Silver Mining Ltd. announced high-grade silver (Ag) results from underground infill drilling at the Plomosas Project in Sinaloa State, Mexico. The results continue to support the potential to increase Ag grades in the Plomosas Mine Area resource. The drilling targeted high grade Ag mineralization in the upper levels of the underground workings, in areas where unsampled intervals from historical drill holes within the 2021 resource block model were previously assigned zero values.

The underground infill drilling program at the Plomosas Mine Area commenced in March 2022 and is ongoing. The drill holes are predominantly short holes planned to target zones where recent geological mapping identified opportunities to improve the 2021 NI 43-101 mineral resource block model Ag grade, utilizing areas of the underground development that provide good access. The underground drilling program is designed to, not only address the shortcomings in the 2021 resource model, but also delineate high-grade Ag-Au mineralized zones located between level 775 RL and 1025 RL.

The underground infill drilling program has a surgical approach using drill rigs with the capacity to drill NQ and BQ diameter holes in selective and tight underground sites, aiming to drill a total of 4,350 m by fourth quarter of 2022. The existing underground infrastructure within the Plomosas Mine, which includes a total of 7.4 km of ramps and galleries, provides flexibility and optimization of the program scheduling, avoiding the need for additional new underground development or long drill holes from surface. A total of 13 holes have been completed underground to date in 2022.

These intervals confirm consistent high-grade Ag mineralization and have also delineated new mineralized zones in areas not previously drilled. Upon completion of the underground infill drill program in fourth quarter of 2022, the Company anticipates commencing a resource upgrade for the Plomosas Mine Area. The drill holes PLIP22-10, PLIP22-11, PLIP22-12 and PLIP22-13 have successfully discovered wide, high-grade Ag mineralization hosted by hydrothermal breccias located in the hanging wall of the previously mined polymetallic (Ag-Au-Pb-Zn) hydrothermal Plomosas Breccia.

This recently mapped zone is located in a section of the Plomosas Mine where the Company initially defined prospective NE-trending faults with potential to host additional Ag-Au only mineralization. These zones were not previously the subject of significant exploration due to the focus on base metals in the historical plant flowsheet. Historical production, and hence exploration, targeted Pb-Zn rich mineralization at the Plomosas Mine.

The drill holes from PLIP22-01 to PLIP22-09 consistently intersected high grade Ag-Au mineralization hosted in a polymetallic (Pb-Zn) hydrothermal breccia. All nine holes indicate the presence of multiple hydrothermal zones with Ag results generally >200 g/t Ag and individual Au grades up to 4.5 g/t Au in locations drilled along strike on the 1025 RL level.