Precious Metals
April 28, 2022

GR Silver Mining (TSX.V: GRSL)

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Delivers Wide, High-Grade Results At Plomosas: 24.2 M At 1,094 G/T Ag, Including 0.6 M At 7,178 G/T Ag

GR Silver Mining Ltd. (TSXV: GRSL) (OTCQB: GRSLF) (FRANKFURT: GPE) – announces wide and high-grade silver (Ag) results from its surface infill drilling program at the Plomosas Project in Sinaloa State, Mexico. These Ag-rich drilling results are part of the Phase I surface infill drilling program initiated in December 2021 at the Plomosas Mine Area, targeting intervals on the upper levels of the historical Plomosas underground mine where unsampled intervals of historical drill holes within the mineralized zone were assigned zero values, and hence affected the grade of model blocks, in the 2021 NI 43-101 mineral resource estimation.

Figure 1: Longitudinal Section Plomosas Mine Surface Infill Drilling Results – Ag Block Model

Figure 2: Plomosas Block Model Cross Section A-A' with Surface Infill Drilling
Figure 3: Plomosas Block Model Cross Section B-B' with Surface Infill Drilling


  • Phase 1 drilling has defined wide, high-grade predominantly Ag-rich mineralization in the upper levels (up to 160 m below surface) of the historical Plomosas Mine.
  • High-grade Ag results (Table 1) include:
  • PLS22-05A: 24.2 m at 1,094 g/t Ag (1,180 g/t AgEq 1 ), including 0.6 m at 7,178 g/t Ag (7,367 g/t AgEq)
  • PLS22-06: 18.2 m at 289 g/t Ag (297 g/t AgEg), including 5.4 m at 690 g/t Ag (701 g/t AgEq)
  • PLS22-04: 13.2 m at 410 g/t Ag (505 g/t AgEq), including 2.8 m at 1,323 g/t Ag (1,447 g/t AgEq)
  • PLS21-36: 9.8 m at 541 g/t Ag
  • PLS21-38: 9.6 m at 486 g/t Ag
  • Closely spaced drilling at Plomosas, with line spacing averaging 50 to 100 m, was designed to obtain representative Ag grades to improve the resource block model.
  • High-grade Ag results suggest potential to significantly increase grade in some areas of the resource model, and hence improve the average
  • Ag grades for the Company's next resource estimation at Plomosas

GR Silver Mining Chairman and CEO, Eric Zaunscherb commented, "From the time of the release of the Technical Report for the Plomosas Project in October 2021, it was clear that new infill drilling could offer the opportunity to improve the grade of the mineral resource estimate by addressing un-sampled or under-sampled areas in the block model. In addition to the expansion of mineralization to depth and along strike at San Marcial, it is GR Silver's priority to address the questions about grade at the Plomosas Mine. After-all, historical production at the Plomosas Mine amounted to 2.5 M tonnes averaging 190 g/t Ag, 0.92 g/t Au, 2.0% Zn and 2.4% Pb. It is deeply satisfying to see the ongoing infill drill program demonstrating grades materially higher than interpolated in the resource model, and over attractive widths."

Plomosas Mine Area - Resource Expansion Program

The infill drilling program at the Plomosas Mine Area commenced in December 2021 and is ongoing. Initially focussing on holes drilled to access unmined areas close to surface, the program is now progressing with a focus on underground infill drilling with three drill rigs.

Surface Infill Drilling

The initial surface infill drilling program was designed to test unmined areas of the Plomosas Mine, located up to 160 m below surface (862 RL to 1025 RL) (see Table 2). The targeted areas are located between old workings and represent sections of the 2021 resource block model where historical drill holes were designated zero grades, resulting in the interpolation of low-grade blocks within the resource model. The 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.

The successful surface infill drilling program has potential to support a significant expansion of high-grade Ag mineralization at the Plomosas Mine. A total of nine holes have been completed on surface to date in 2022. Major highlights from the initial six 2022 holes, and four 2021 holes, are summarized in Table 1. These intervals confirm consistent high-grade Ag mineralization in areas of previously unsampled historical drill hole intervals, where a zero Ag grade was applied in the NI 43-101 report issued on October 8, 2021. The results also confirm the presence of predominantly high-grade Ag zones close to the surface in unmined areas (Figure 1).

Additional drilling is anticipated, as part of the current underground infill drilling program. Upon completion of the 2022 drill program, the Company anticipates commencing a resource upgrade for the Plomosas Mine Area.

Underground Infill Drilling

As a result of the Company's underground mapping and sampling program in the Plomosas Mine over the past six months, the Company is confident that high-grade Ag mineralization can be defined where the NI 43-101 resource block model currently has interpolated low-grade Ag material. The total infill drilling program currently scheduled for 2022 anticipates drilling a total of 7,300 m, between surface and the 775 level, which is 250 m below the surface. The existing underground infrastructure within the Plomosas Mine, including ramps and galleries, provides flexibility and optimization of the program, avoiding additional underground development.

Infill Program – Discussion of Results

The drill holes PLS22-03, PLS22-04, PLS22-05A and PLS22-06 targeted the mapped high-grade Ag mineralization, which was identified on surface, with underground continuity, when validating the current resource model. The Ag resource model displayed low-grade Ag mineralization and was inconsistent with the high-grade mineralization the Company encountered during the mapping process. All four holes indicate the presence of multiple hydrothermal zones with Ag results >1,000 g/t Ag hosted by a wide hydrothermal breccia with consistent mineralization over its length.

PLS22-05A achieved an exceptional Ag-rich interval comprising 24.2 m at 1,094 g/t Ag. Within this interval, results are consistently high-grade, with individual samples up to 7,117 g/t Ag reinforcing the presence of high grades in sections of the current resource model where the Company believes that the interpolated Ag grades are underestimated (Figure 2).

Drill holes PLS21-36 and PLS21-37, as well as PLS21-38 (Figure 3) are located adjacent to mined areas where a low density of historic drilling resulted in only low-grade Ag mineralization being allocated to the relevant blocks within the current NI 43-101 model. There is a predominance of Ag and an absence of base metal mineralization (Pb-Zn) in the hydrothermal breccias intersected by these drill holes, as illustrated by PLS21-36 with 9.8 m at 541 g/t Ag.

The drill hole PLS21-39 is located at the northern end of the current resource model and encountered intensive hydrothermal alteration, however cross-cutting faults appear to displace the main Plomosas Breccia at this extremity. Recent surface mapping in an area named Las Cuevas, immediately 1.3 km north of this hole location, has recently identified the presence of mineralization on surface and additional drilling is being considered to better delineate the Ag mineralization beyond the current northern limit of the existing NI 43-101 resource model.

Drill holes PLS22-01 and PLS22-02 are located in the vicinity of a small historical underground development named Plomositas. Preliminary drilling results at Plomositas indicate the presence of gold-bearing structures up to 3.0 m wide and potential displacement of the main Plomosas Breccia, at the northern end of the current resource model, resulting from E-W regional faulting.

Disclaimer: GR Silver is a paid marketing client*

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