GR Silver Mining (TSXV: GRSL) (OTCQB: GRSLF) (FRANKFURT: GPE) – announces first assay results from the 2022 resource expansion drill program at the San Marcial Area in Sinaloa, Mexico. The high-grade silver ("Ag") results demonstrate the potential for resource expansion both near-surface and at depth at the San Marcial Area. The 23 released drill holes targeted delineation of near-surface high-grade zones, as well as the lateral continuation of mineralization along the prospective contact between the upper andesitic "block and ash" unit and lower volcano-sedimentary units. This contact commonly hosts the San Marcial Area Ag mineralization (Figure 1). Results from the remaining drill hole of the 2021 program, which targeted NW strike extensions of the mineralized hydrothermal breccia, are also reported in this news release.
The success of the 2022 drilling has led the Company to extend its program further to the SE of the southern limit of the current NI 43-101 San Marcial Resource Area ("NI 43-101"). Additional drilling will continue to target new discoveries along strike, following the key geological contact zone (Figure 2).
Major highlights of the 23 holes are summarized as follows:
- Attractive high-grade Ag results at shallow depth with the potential to increase Ag grades in the updated resource estimation scheduled for Q1|23, including:
- SMSP22-003: 15.4 m at 547 g/t Ag, including 2.0 m at 1,179 g/t Ag
- SMSP22-012: 15.0 m at 324 g/t Ag, including 1.0 m at 1,541 g/t Ag
- SMS22-02: 2.8 m at 455 g/t Ag, including 0.3 m at 3,854 g/t Ag
- SMSP22-010: 16.7 m at 193 g/t Ag, including 2.0 m at 921 g/t Ag
- Near surface Ag resource (0-20 m depth) within the NI 43-101 had limited previous drilling. This is now addressed with shallow, high-grade Ag intercepts from the current program.
- The San Marcial mineralization is hosted by breccias along the contact between two different volcanic units: an upper unit represented by andesitic "block and ash", and a lower unit represented by lapilli-ash tuffs. Recent mapping and geochemical sampling have confirmed the presence of Ag anomalies immediately SE of the NI 43-101.
- An initial drill program is in progress to the SE of the NI 43-101 in some of these Ag anomalies, testing extensions along the key mineralized contact zone, where high-grade Ag hydrothermal breccias and related Ag-Au mineralization are present.
GR Silver Mining Chairman and CEO, Eric Zaunscherb commented, "It is very exciting to see exploration concepts, like the potential for additional high grade precious metal mineralization extending to the SE of San Marcial, come to fruition. Recent results not only demonstrate this potential but also the potential for targeted infill drilling to capture the presence of near-surface, high-grade Ag and Au zones in the upcoming NI 43-101 update. Ongoing drilling is certainly proving the importance of understanding the structural controls on high-grade mineralization, with mounting anticipation of new discoveries as the geological onion is peeled."
Shallow Drill Program 2022
The NI 43-101 Report (see News Releases dated February 7, 2019 and June 12, 2020) indicated the potential for a significant portion of the resource to be open pit amenable. The Company recognized an opportunity to increase near surface grades of the Ag-rich hydrothermal breccia, which was neither mapped/sampled in detail in 2019, nor fully incorporated into the NI 43-101. The breccia hosted mineralization on surface displays consistency of Ag grades over mineable widths and is exposed in numerous locations along 500 m of strike length. A shallow drill program was instigated early this year, designed to confirm the theory of high-grade continuity with diamond drill core that can be used in the NI 43-101 update, scheduled for Q1|23.
This program will aid the delineation of the shallow (0-20 m depth) high-grade breccia limits and, is likely to result in an increase in Ag grades in the resource model near surface. As a reference, the resource table from the NI 43-101 Report indicates an average Ag grade in the "OP Breccia" of 202 g/t Ag (Indicated) and 131 g/t Ag (Inferred). Results thus far from the 2022 shallow drill program (Figure 2), such as 15.4 m at 547 g/t Ag (SMSP22-003) and 15.0 m at 324 g/t Ag (SMSP22-012), indicate potential for Ag grades in the breccia near surface to exceed those estimated in the NI 43-101 Report (Figure 1). The shallow drill program continues within the NI 43-101.
SE Resource Extension Drill Program
The San Marcial mineralization is hosted by hydrothermal breccias along the NW-SE trending, and NE dipping, contact between two different (upper and lower) volcanic units.
The 2022 surface drilling aims to test the extensions of the mineralization along the target contact zone, further to the SE (Figure 2). Field investigations have confirmed the geological contact along 1.5 km and further geochemical sampling has identified seven Ag exploration targets. This drill program is in progress at the first target, which is located on confirmed surface Ag mineralization similar to the mineralization found in the San Marcial Resource Area.
Initial results from drilling to the SE of the NI 43-101 have also confirmed Ag mineralized hydrothermal breccias along the contact, similar to those in the NI 43-101, as well as the presence of the Au mineralized footwall stockwork systems. As an example, drill hole SMS22-02 returned 2.8 m at 455 g/t Ag, including a high-grade Ag core over 0.3 m at 3,854 g/t Ag, in addition to 0.7% Pb and 1.6% Zn (Table 1). Final results from hole SMS22-05 are pending, while samples from three additional completed drill holes are in the laboratory for analysis, and two drill holes are currently in progress. The drill program in the SE Resource Extension is ongoing and geological investigations continue along the unexplored 500 m of this potential geological contact.
Drilling Au Targets NW of the Resource Area
Two of the completed drill holes from the 2022 program targeted extensions to the breccia-hosted Ag mineralization, as well as confirmation of high-grade Au veins, to the NW of the NI 43-101 (Figure 2). One completed drill hole in the NW, with samples currently at the laboratory (SMS22-07), targeted an area where the Company drilled a high-grade Au intercept of 1 m at 204.6 g/t Au in 2019 in drill hole SM-19-01 (see News Release dated July 30, 2019). The update to the 2019 NI 43-101 will also integrate Au mineralized zones and veins into the resource model.
Deep Drilling Program
The 2021 underground drill program at San Marcial successfully extended the mineralization down dip more than 150 m below the base of the border defined within the NI 43-101, supporting the Company's theory of SE plunging high-grade Ag-mineralized shoots within the broader San Marcial Breccia. It also confirmed the presence of multiple mineralization styles, with a wide, low-grade stockwork-hosted Au zone hosted within the volcano sedimentary unit in the footwall, immediately below the San Marcial Breccia mineralization.
The Company re-commenced the drill program in Q2|22 using existing drill pads on surface and targeting the extension of the high-grade Ag mineralization up to 300 m below the base of the 2019 resource model. The previous high-grade Ag results of (5.6 m at 1,792 g/t Ag in SMI21-03 and 3.5 m at 1,002 g/t Ag in SMI21-04), combined with more detailed underground structural mapping, are encouraging the Company to continue drill-testing the extensions of high-grade zones down-plunge. These extensions have the potential to delineate additional resources to be incorporated in the planned mineral resource update.
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