GR Silver Mining Delivers Positive Progress on Phase II Underground Sampling at Plomosas Mine
GR Silver Mining Delivers Positive Progress
on Phase II Underground Sampling at
Plomosas Mine
VANCOUVER, BC
,
Oct. 15, 2025
/CNW/ - GR Silver Mining Ltd. ("GR Silver Mining" or the
"Company") (TSXV: GRSL) (OTCQB: GRSLF) (FRANKFURT: GPE) is pleased to report the results
of
Phase II of the Bulk Sample Test Mining Program (the "BSTM")
at the
Plomosas Mine
,
located in
Sinaloa, Mexico
. The BSTM is progressing towards the following key objectives:
1
.
Delineation of Accessible Areas:
Further define and map accessible underground areas in the historic Plomosas Mine for BSTM.
2
.
Identification of High-Grade Previously blasted, Mineralized Material:
Locate high-grade previously blasted, mineralized material that is accessible for future
processing. During Phase II mapping and channel sampling in 21 underground areas, previously
blasted mineralized material was identified in multiple locations inside the mine.
3
.
Metallurgical Test Work and Process Definition:
Collect representative samples to confirm recoveries estimated by previous test work and
establish process design criteria (including work indices) that will be the basis for preliminary
flow sheets and technical specifications.
4
.
Underground Sampling Progress:
Continue underground sampling across
21 selected sites
to enhance reconciliation between the
March 2023
NI 43-101 Mineral Resource Estimate (MRE) and the areas targeted for bulk
sampling as part of the BSTM program.
Initial BSTM Highlights from the Additional Underground Channel Sampling Program:
Level 975
6.7 m
at 1,040 g/t AgEq
*, consisting of
903 g/t Ag, 0.03 g/t Au, 1.4% Pb, and 1.7% Zn
1.2 m
at 2,365 g/t AgEq
, consisting of
2,264 g/t Ag, 0.08 g/t Au, 0.5% Pb, and 0.9% Zn
Ramp 3
4.2 m
at 1,018 g/t AgEq
, consisting of
49 g/t Ag, 5.12 g/t Au, 6.9% Pb, and 5.9% Zn
,
including
0.5 m
at 2,256 g/t AgEq
, consisting of
102 g/t Ag, 35.7 g/t Au, 4.3% Pb, and 14.2% Zn
GR Silver Mining's President and CEO,
Marcio Fonseca
, commented
"
Ongoing underground
channel sampling at the historic
Plomosas Mine
has delineated additional
high-grade mineralized
zones
that are accessible for future
BSTM
. In addition, the program has identified previously
blasted mineralized material
suitable for future processing.
The confirmation of sulphide–rich,
unmined areas that also contain high-grade silver and gold mineralization further supports the
Company's plans to advance the implementation of the BSTM at Plomosas. The Company is also
progressing process design criteria that will be the basis of preliminary flowsheet design and initial
engineering and costing studies. This includes the development of technical specifications that will
be the basis for process equipment selection. In conjunction with the assessment of preliminary
pilot plant configurations, initial costs for the process portion of BSTM will be developed. Additional
metallurgical test work on representative samples collected from the historic mine are also being
completed to corroborate previous test work that showed strong recoveries of silver, gold, lead,
and zinc".
Underground Sampling Program Progress
The Company recently completed a two-phase underground sampling program at the Plomosas
Mine as part of the ongoing Bulk Sampling Test Mining Program.
Phase I focused on collecting representative samples for metallurgical test work (including recovery
estimates and determination of process design criteria) to support process plant design and process
evaluation. Phase II expanded the program, generating a significantly larger dataset to refine mine
engineering parameters, grade distribution, and mine planning.
The previously blasted mineralized material is being systematically sampled and analyzed to
determine geology, particularly massive sulfide mineralized material, and processing parameters for
potential process in the near future once BSTM is more advanced.
Importantly, Phase II results have detailed the presence of massive sulphide-rich, high-grade silver
zones, composed primarily of galena and sphalerite, hosted within hydrothermal breccias. These
zones (Figure 1) occur in areas where the MRE supports the potential for additional underground
drilling and an updated MRE targeted for 2026.
A detailed summary of the Phase II selective samples is provided in Table I.
Table 1 Phase II Underground Channel Sampling Assay Results, Plomosas Mine
Table 1 Phase II Underground Channel Sampling Assay Results, Plomosas Mine (CNW Group/GR
Silver Mining Ltd.)
Table 1 Phase II Underground Channel Sampling Assay Results, Plomosas Mine (cont.)
Table 1 Phase II Underground Channel Sampling Assay Results, Plomosas Mine (cont.) (CNW
Group/GR Silver Mining Ltd.)
Note:
Numbers may be rounded. Results are uncut and undiluted. True width not estimated as the Company does not have sufficient data from the new mineralized zones to determine
the true widths of the intervals with any confidence.
* Ag Eq calculations using US$20.00/oz Ag, US$1,600/oz Au, US$0.90/lb Pb, US$1.10/lb Zn and US$3.00/lb Cu, with metallurgical recoveries of Ag – 74%, Au – 86%, Pb – 69%,
Zn – 75% and Cu – 80%. Ag Eq = ((Ag grade x Ag Price x Ag recovery) + (Au grade x Au price x Au recovery) + (Pb grade x Pb price x Pb recovery) + (Zn grade x Zn price x Zn
recovery) + (Cu grade x Cu price x Cu recovery)/(Ag price x Ag recovery)
Advancement of Engineering and Mine Assessment Activities
The Company has completed a detailed laser survey of the historic Plomosas Mine and accessible
infrastructure across approximately 7.4 km of underground development. (
https://grsilvermining.com/investor-downloads/
).
As previously noted previously blasted mineralized material—blasted by Grupo México in the early
2000s—has been identified. This material represents potential sources of feed for the planned
BSTM in the future.
The areas selected for Phases I and II of the program host continuous unmined zones of silver, gold,
and base metal mineralization, with grades considered attractive for advancing a BSTM, targeted to
commence in early 2026. Implementation of the BSTM may include the construction of an on-site
pilot processing plant, with detailed process parameters, engineering design, and costing to be
finalized following completion of Phase II.
Building on the success of recent sampling results, GR Silver Mining plans to continue exploring and
evaluating additional high-grade silver zones identified in the MRE, which may further enhance the
implementation of the BSTM. In parallel, the Company is also reviewing opportunities in the
surrounding Plomosas district, including existing processing facilities, for potential integration into the
BSTM framework.
Figure 1 3D Long-Section View of the Plomosas Mine Workings with Areas Selected for Phase II
Sampling. (CNW Group/GR Silver Mining Ltd.)
Note: Purple shapes are potential stope blocks for BSTM. Pale grey represents existing underground developments of varying sizes, ramps and historical stopes.
Leadership Changes
The Company announces that it has accepted the resignation of Mr.
Alejandro Cano
, Vice President,
Operations, who will be departing the Company effective
October 15, 2025
. The Company is
reviewing senior candidates for this operational position as it ramps up its BSTM.
The Company is also pleased to announce that Mr.
Robert Payment
, currently serving as Chief
Financial Officer (CFO), has assumed the additional role of Corporate Secretary, effective
immediately. Mr. Payment succeeds Mr.
Blaine Bailey
, who is retiring from the position. The
Company extends its sincere appreciation to Mr. Bailey for his dedication and valuable contributions
throughout his tenure.
The Company would like to thank Mr. Cano and Mr. Bailey for their commitment and leadership
during their time with the Company. We wish them both continued success in their future endeavors.
As we move forward, we remain focused on strengthening our operations and maintaining the
momentum of our growth and development initiatives at the Plomosas Project.
About the Plomosas Project
The Plomosas Project, including the recent high-grade silver discovery in the San Marcial SE Area,
is progressing in 2025 as an emerging high-grade silver district located in southwestern edge of the
Sierra Madre Occidental,
Sinaloa, Mexico
. The Plomosas Project, covering 7,823 ha, including the
historical Plomosas Underground mine. benefits from mine infrastructure, road access and existing
permits associated with past-producing mining sites. The district contains intermediate to low-
sulfidation epithermal silver and gold mineralization, hosted in hydrothermal breccias and veins.
Recent success in exploration and drilling has delineated wide, high-grade, shallow hydrothermal
breccias in the San Marcial Area, including the SE Area discovery, where step-out drilling is
underway in 2025, aiming for continuous resource growth. At the historical Plomosas Mine, where
Grupo Mexico operated the underground mine from 1985 to 2000, exploration, underground
sampling and metallurgical programs are being conducted to support future decisions regarding the
implementation of a Bulk Sampling Test Mining Program.
QA/QC Procedures
The Company has implemented QA/QC procedures, which include the insertion of blank, duplicate,
and standard samples in all sample lots sent to SGS de México, S.A. de C.V. laboratory facilities in
Durango, Mexico
, for sample preparation and assaying. For every sample with results above Ag >
100 ppm (over the limit), these samples are re-assayed by SGS de
Mexico
. Core samples are
represented by both HQ and NQ diameters and samples are represented by ½ core split of original
core. The analytical methods include four acid Digestion and Inductively Coupled Plasma Optical
Emission Spectrometry, with Lead Fusion Fire Assay and a gravimetric finish for silver above over
limits. For gold assays, the analytical methods are Lead Fusion and Atomic Absorption
Spectrometry, Lead Fusion Fire Assay, and gravimetric finish for gold above over limits (>10 ppm).
Qualified Person
The Qualified Person under National Instrument 43-101 Standards of Disclosure for Mineral Projects
for this news release is
Marcio Fonseca
, P. Geo., President & CEO for GR Silver Mining, who has
reviewed and approved its contents.
About GR Silver Mining Ltd
.
GR Silver Mining is a Canadian-based,
Mexico
-focused mineral exploration company engaged in
cost-effective silver-gold resource expansion on its 100%-owned assets, located on the eastern
edge of the Rosario Mining District, in the southeast of Sinaloa State,
Mexico
. GR Silver Mining
controls 100% of the Plomosas Project, including the former Plomosas underground mine and wide,
high-grade silver mineralized zones at the San Marcial Area. Recent discoveries in the 78 km² of
highly prospective, advanced-stage exploration concessions position the Company well for resource
expansion at the Plomosas Project.
GR Silver Mining Ltd.
Márcio Fonseca, President & CEO
Cautionary Statement Regarding Forward-Looking Information
This press release contains "forward-looking statements" within the meaning of applicable
Canadian securities legislation and information that are based on the beliefs of management and
reflect the Company's current expectations. When used in this press release, the words "estimate",
"project", "belief", "anticipate", "intend", "expect", "plan", "predict", "may" or "should" and the
negative of these words or such variations thereon or comparable terminology are intended to
identify forward-looking statements and information. Such statements and information reflect the
current view of the Company. Risks and uncertainties may cause actual results to differ materially
from those contemplated in those forward-looking statements and information. By their nature,
forward- looking statements involve known and unknown risks, uncertainties and other factors
which may cause our actual results, performance or achievements, or other future events, to be
materially different from any future results, performance or achievements expressed or implied by
such forward-looking statements.
SOURCE
GR Silver Mining Ltd.
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For further information:
For further information, please contact: Telephone: +1 236-270-2057,
Email: [email protected]
CO: GR Silver Mining Ltd.
CNW 05:00e 15-OCT-25