GR Silver Mining Ltd. announced that it has advanced underground development and bulk sampling test mining ("BSTM") at the San Juan Area, Plomosas Project in Mexico. The BSTM program is progressing under a commercial agreement with private local operators (mining and milling operators) in the Rosario Mining District in Sinaloa. The Company has achieved the following milestones: To date, 280 m of underground development have been completed, and 15,170 t of BSTM material have been processed from the San Juan Area, from which 235 t of concentrate have been produced.

The processing of BSTM material from the San Juan Area has resulted in silver recoveries ranging from 84% to 92% and gold recoveries ranging from 60% to 75%. The BSTM program has allowed the processing of lead concentrates containing high-grade silver and gold to be commercially acceptable by off-takers. The work on-site supports the definition of a high-grade silver-gold zone not represented in the current NI 43-101 Mineral Resource estimate, allowing better delineation of key geological controls hosting significant mineralization for future drilling.

The channel sampling program, as part of the BSTM program, has reported high-grade results, including 2.5 m @ 1,625 g/t Ag and 14.1 g/t Au. This new zone was recently discovered, hosted by a vein/hydrothermal breccia within a NE-trending fault zone in the San Juan Area. These structures were not integrated in the current NI 43-101 Mineral Resource estimate, creating potential for future resource expansion in the San Juan Area.

Underground control sampling during the BSTM program and site preparation has revealed new geological structures hosting silver- and gold-rich hydrothermal breccias not previously incorporated in the geological model. The BSTM activities will focus on the San Juan and La Colorada Areas due to the proximity of the targets to the surface and to third party-owned processing plants. The Company is assessing the implementation of a similar BSTM program at the Plomosas Mine Area in the near term.

Bulk sampling test mining within these historical mines is expected to continue throughout 2024. The activities of the BSTM program in the Plomosas Project's historical mines are providing the Company with a low-cost platform for the definition of new targets for drilling, discovery and, potentially, resource expansion, adding key information for future project development.