Vancouver, British Columbia--(Newsfile Corp. - September 22, 2026) - Minaurum Silver Inc. (TSXV: MGG) (OTCQX: MMRGF) ("Minaurum" or the "Company") is pleased to report that ongoing underground rehabilitation efforts have resulted in safe access to a large section of the main haulage level and a 55-metre-deep internal shaft leading to lower levels of its historic Promontorio mine. These advancements support modern exploration efforts with preliminary channel sampling returning high-grade silver at the Promontorio Vein Zone within the high-grade Alamos Silver Project ("Alamos") in Sonora, Mexico.
Underground channel sampling conducted across mineralized structures along the edges of historically mined stopes returned the following highlights:
- 0.30 m of 4,142 g/t silver equivalent ("AgEq") (Table 1)
(3,860 g/t Ag, 0.42 g/t Au, 1.91% Cu, 1.58% Pb, 2.21% Zn) (Sample 101307) - 0.50 m of 704 g/t AgEq
(275 g/t Ag, 1.23 g/t Au, 0.34% Cu, 0.39% Pb, 13.35% Zn) (Sample 101277) - 0.50 m of 733 g/t AgEq
(282 g/t Ag, 2.67 g/t Au, 0.36% Cu, 0.52% Pb, 8.07% Zn) (Sample 101276) - 0.50 m of 480 g/t AgEq
(386 g/t Ag, 0.12 g/t Au, 0.69% Cu, 0.27% Pb, 0.82% Zn) (Sample 101297)
"Minaurum's 28.6 Moz AgEq inferred resource at Promontorio represents a significant portion of the Alamos Project's 55.2 Moz AgEq initial resource estimate. With more than 600 m of the haulage level and the 55 m-deep Balvanera shaft now securely accessible, we have begun detailed underground mapping and sampling that is already returning encouraging results," stated Darrell Rader, President and CEO. "We look forward to advancing rehabilitation, mapping and sampling across the historic Promontorio, Quintera and Minas Nuevas mines."
Promontorio Mine History - Promontorio Vein Zone Resource and Potential
The Promontorio mine produced an estimated 70 million ounces of silver historically with underground and surface mine workings traced for more than 1 km. Sampling and mapping of mine dumps at Promontorio revealed a 1 m-wide boulder of massive sulfide vein assaying 3,320 g/t Ag, 54.7 g/t Au, 25% Cu, 6.5% Pb, and 1.1% Zn, an indication of the high grades exploited by early miners (see news release dated November 15, 2022).
The Promontorio vein zone accounts for 28.6 Moz AgEq of Minaurum's total inaugural inferred resource estimate of 55.2 Moz AgEq (34.8 Moz Ag, 35.6 Koz Au, 50.99 Mlbs Cu, 114.77 Mlbs Pb, and 237.80 Mlbs Zn) from the Europa, Promontorio, and Travesia vein zones. Geological mapping and drilling show potential for resource expansion at Promontorio at depth and along strike (see news release dated January 28, 2026).
Historical maps and reports show the Promontorio Mine to consist of a haulage level extending approximately 1,200 m with crosscuts, shafts, and raises connecting to stopes and lower and upper levels. The Dios Padre and Azulacas shafts connect the northern part of the workings to the surface, while the internal Balvanera and Tirito shafts provide access to at least two lower levels and numerous crosscuts and stopes as indicated by historical lower levels from the haulage level maps (Figures 1 and 2).
Rehabilitation Work
Crews have secured access and installed lighting to the first 600 m of the Promontorio mine's haulage level and have installed pumps in the Tirito and Balvanera shafts. In the 55 m-deep Balvanera shaft, crews installed a marine ladder to 45 m with 2 rest stations and a bridge leading to an open lower level at 20 m. Levels at 12 and 45 m are blocked by backfill and flooded, respectively. Clean-up and ladder installation in the Tirito shaft is pending. Water lines lead from the shafts to a water tank situated outside the mine portal. The Company previously drilled and cased holes from the surface into the Promontorio mine near the Balvanera and Tirito shafts in order to run electricity, water, and compressed air for lighting, pumps, and ventilation (see news release dated November 22, 2022) (Figures 3-6).
The accessible parts of the Promontorio mine have been surveyed using a LIDAR scanning survey system which has provided detailed images of the underground workings, which are used as the base for geological mapping and sampling. The LIDAR surveys are integrated into the project's topographical model which includes all drill-collar and down-hole surveys, providing an exact and precise data set, further refining the geological model at Alamos.
Figure 1. Promontorio mine map, indicating rehabilitated portions, service holes, and internal and surface shafts. Click to enlarge.
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Figure 2. Longitudinal section of Promontorio mine showing relationship of workings to January 2026 estimated inferred resource. Click to enlarge
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Figure 3. Balvanera shaft hoist room. Note yellow safety railing around Balvanera shaft collar at center-right of image and gray electrical control panel in center-left background. Orange air duct leads into shaft to provide ventilation. Steel casing slanting from right to left in left foreground contains electrical cable from for lighting and welding and other tools. The wooden beam above the shaft collar is a vestige of historical hoisting equipment.
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Figure 4. view down 55 m-deep Balvanera shaft. Note historical timbered shaft walls, recently installed marine ladder and ventilation duct. The ladder reaches 45 m depth and provides access to 3 lower levels at 12, 20, and 45 m.
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Figure 5. Portion of Promontorio haulage level with newly installed lighting and water line.
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Figure 6. View of portion of Promontorio vein zone in immediate hanging wall of fault plane, Tirito shaft area.
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Underground Geological Mapping and Geochemical Sampling
Minaurum geologists produced a 1:250-scale geological map of the haulage level from the entrance to the Balvanera shaft and collected wall-rock and backfill samples (Figures 7 and 8). The first 200 m of the haulage level passes through andesitic agglomerate before encountering the northwest-southeast fault that truncates the Promontorio vein zone nearly perpendicularly and separates it from the Promontorio Sur zone near the Tirito shaft. The fault zone is 1 to 5 metres wide, with the southwest side downthrown by several hundred meters, and it contains angular fragments of mineralized vein material. The haulage level continues to the north of the northwest-southeast fault in the hanging wall (western side) of the Las Guijas vein, with crosscuts exposing the vein zone in skarn and in granodiorite. Assays of selected elements of rock channel and grab samples are listed in Table 1 and their positions shown in Figures 7 and 8.
Highlights of channel samples include 0.30 m of 4,142 g/t AgEq and 0.50 m of 704 g/t AgEq.
Table 1. Assays for selected elements of rock samples, Promontorio mine. Sample locations appear on Figures 7 and 8. Weight-averaged silver-equivalent grades (AgEq g/t) are based on the October 1, 2025 Long-term CIBC Global Mining Group Analyst Consensus Commodity Price Forecast: Ag $29.73/tr oz, Au $2,646/tr oz, Cu $4.34/lb, Pb $0.92/lb, Zn $1.21/lb. Metallurgical recovery assumption: 88.3% for Ag, 88.5% for Au, 75.5% for Cu, 83% for Pb, 75% for Zn.
| Sample | Width
(m) | Ag
g/t | Au
g/t | Cu
% | Pb
% | Zn
% | AgEq
g/t |
| 101275 | 0.50 | 35 | 0.03 | 0.06 | 0.31 | 5.27 | 161 |
| 101276 | 0.50 | 282 | 2.67 | 0.36 | 0.52 | 8.07 | 733 |
| 101277 | 0.50 | 275 | 1.23 | 0.34 | 0.39 | 13.35 | 704 |
| 101278 | 0.60 | 283 | 1.62 | 0.20 | 0.37 | 6.78 | 595 |
| 101280 | 0.30 | 38.9 | 0.02 | 0.02 | 0.18 | 2.46 | 98 |
| 101281 | 0.50 | 217 | 1.01 | 0.29 | 4.92 | 12.55 | 696 |
| 101282 | 0.30 | 30.3 | 0.44 | 0.39 | 5.20 | 8.14 | 380 |
| 101283 | 0.40 | 23.9 | 0.12 | 0.01 | 1.48 | 3.52 | 140 |
| 101284 | 0.50 | 22.1 | 2.26 | 0.15 | 0.12 | 0.90 | 258 |
| 101285 | 0.40 | 27.2 | 0.89 | 0.14 | 0.11 | 0.40 | 130 |
| 101286 | 0.50 | 2.53 | 0.01 | 0.01 | 0.22 | 0.38 | 16 |
| 101287 | 0.50 | 20.7 | 0.05 | 0.02 | 1.50 | 3.24 | 125 |
| 101288 | 0.55 | 5.67 | 0.23 | 0.00 | 0.11 | 0.17 | 32 |
| 101289 | 0.50 | 14.8 | 0.00 | 0.02 | 0.10 | 0.06 | 20 |
| 101290 | 0.60 | 12.6 | 0.00 | 0.01 | 0.03 | 0.03 | 15 |
| 101291 | 0.40 | 100 | 0.19 | 0.51 | 0.05 | 0.03 | 163 |
| 101292 | 0.55 | 9.16 | 0.00 | 0.01 | 0.02 | 0.03 | 12 |
| 101293 | 0.55 | 14.5 | 0.01 | 0.05 | 0.20 | 0.14 | 27 |
| 101294 | 0.50 | 12.35 | 0.01 | 0.09 | 0.14 | 0.20 | 28 |
| 101295 | 0.55 | 55.7 | 0.10 | 0.47 | 0.58 | 2.07 | 161 |
| 101296 | 0.80 | 52.6 | 0.06 | 0.08 | 0.12 | 0.11 | 69 |
| 101297 | 0.50 | 386 | 0.12 | 0.69 | 0.27 | 0.82 | 480 |
| 101298 | 0.60 | 22.2 | 0.05 | 0.10 | 0.07 | 0.42 | 45 |
| 101300 | 0.50 | 0.87 | 0.01 | 0.01 | 0.01 | 0.01 | 3 |
| 101301 | 0.50 | 0.79 | 0.00 | 0.01 | 0.01 | 0.01 | 2 |
| 101302 | 0.50 | 1.18 | 0.00 | 0.02 | 0.01 | 0.02 | 4 |
| 101303 | 0.60 | 0.49 | 0.00 | 0.00 | 0.01 | 0.02 | 1 |
| 101304 | 0.50 | 5.76 | 0.00 | 0.01 | 0.20 | 0.03 | 12 |
| 101305 | 0.60 | 0.71 | 0.00 | 0.00 | 0.01 | 0.03 | 2 |
| 101306 | 0.50 | 9.01 | 0.01 | 0.04 | 0.18 | 0.26 | 23 |
| 101307 | 0.30 | 3860 | 0.42 | 1.91 | 1.58 | 2.21 | 4142 |
| 101308 | 0.50 | 39.6 | 0.04 | 0.06 | 0.21 | 0.14 | 55 |
Figure 7. Geological map of accessible portion of Promontorio mine, showing locations and AgEq values of rock samples. See Figure 8 for inset map of Tirito area. Click to enlarge.
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Figure 8. Geological map of Tirito shaft area of Promontorio mine. Click to enlarge.
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Future Underground Rehabilitation
Further underground rehabilitation work will be undertaken at workings at the Quintera mine (Quintera Vein Zone) in the central area, and the Minas Nuevas, Cotera, and Pulpito Vein Zones in the northern part of the Alamos project area.
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Minaurum Silver Inc. (TSXV: MGG) (OTCQX: MMRGF) (FSE: 78M0) is an Americas-focused explorer concentrating on the high-grade 100% owned, production-permitted Alamos silver project in southern Sonora, Mexico and the Lone Mountain CRD Project in Nevada, USA. Minaurum is managed by one of the strongest technical and finance teams and will continue its founders' legacy of creating shareholder value by acquiring and developing a pipeline of Tier-One precious-and base metal projects.
ON BEHALF OF THE BOARD
"Darrell A. Rader"
Darrell A. Rader
President and CEO
For more information, please contact:
Sunny Pannu - Investor Relations and Corporate Development Manager
The TSX Venture Exchange does not accept responsibility for the adequacy or accuracy of this news release.
________________________________________________________________________
Data review and verification: Stephen R. Maynard, Vice President of Exploration of Minaurum and a Qualified Person (QP) as defined by National Instrument 43-101, reviewed and verified the assay data, and has approved the disclosure in this news release. Verification was done by visual inspection of core samples and comparison to assay results. Assay results have not been checked by re-analysis. No factors were identified that could materially affect the accuracy or reliability of the data presented in this news release.
Analytical Procedures and Quality Assurance/Quality Control: Preparation and assaying of drilling samples from Minaurum's Alamos project are done with strict adherence to a Quality Assurance/Quality Control (QA/QC) protocol. Core samples are sawed in half and then bagged in a secure facility near the site and then shipped either by a licensed courier by Company personnel to ALS Minerals' preparation facility in Hermosillo, Sonora, Mexico. ALS prepares the samples, crushing them to 70% less than 2mm, splitting off 250g, and pulverizing the split to more than 85% passing 75 microns. The resulting sample pulps are prepared in Hermosillo and then shipped to Vancouver for chemical analysis by ALS Minerals. In Vancouver, the pulps are analyzed for gold by fire assay and ICP/AES on a 30-gram charge. In addition, analyses are done for silver, copper, lead, and zinc using 4-acid digestion and ICP analysis. Samples with silver values greater than 100 g/t; and copper, lead, or zinc values greater than 10,000 ppm (1%) are re-analyzed using 4-acid digestion and atomic absorption spectrometry (AAS).
Quality-control (QC) samples are inserted in the sample stream every 20 samples on average, and thus represent 5% of the total samples. QC samples include standards, blanks, and duplicate samples. Standards are pulps that have been prepared by a third-party laboratory; they have gold, silver, and base-metal values that are established by an extensive analytical process in which several commercial labs (including ALS Minerals) participate. Standards test the calibration of the analytical equipment. Blanks are rock material known from prior sampling to contain less than 0.005 ppm gold; they test the sample preparation procedure for cross-sample contamination. In the case of duplicates, the sample interval is cut in half and then quartered. The first quarter is the original sample, the second becomes the duplicate. Duplicate samples provide a test of the reproducibility of assays in the same drilled interval. When final assays are received, QC sample results are inspected for deviation from accepted values. To date, QC sample analytical results have fallen in acceptable ranges on the Alamos project.
When final assays are received, QC sample results are inspected for deviation from accepted values by the QP. To date, QC sample analytical results have fallen in acceptable ranges on the Alamos project.
ALS Minerals is independent of Minaurum Silver and is independent of the Qualified Person.
Cautionary Note Regarding Forward-Looking Information: This news release contains "forward-looking information" within the meaning of applicable Canadian securities legislation. "Forward-looking information" includes, but is not limited to, statements with respect to the activities, events or developments that the Company expects or anticipates will or may occur in the future, including the Resource Estimate; the ongoing Phase II 50,000 m resource expansion drill program; and the completion of an updated resource estimate in the second half of 2026. Generally, but not always, forward-looking information and statements can be identified by the use of words such as "plans", "expects", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", or "believes" or the negative connotation thereof or variations of such words and phrases or state that certain actions, events or results "may", "could", "would", "might" or "will be taken", "occur" or "be achieved" or the negative connotation thereof.
In making the forward-looking information in this release, Minaurum has applied certain factors and assumptions that are based on Minaurum's current beliefs as well as assumptions made by and information currently available to Minaurum, including that Minaurum will be able to obtain all necessary permits and approvals for planned exploration and drilling activities; that Minaurum's planned drilling and exploration activities will be completed on the expected timeline, or at all; that the results of the drilling and exploration activities will be as expected; that Minaurum will be able to complete the updated mineral resource estimate on the timelines expected, or at all; and that Minaurum will have the financial resources to complete its ongoing drill program and anticipated updated mineral resource estimate. Although Minaurum considers these assumptions to be reasonable based on information currently available to it, they may prove to be incorrect, and the forward-looking information in this release are subject to numerous risks, uncertainties and other factors that may cause future results to differ materially from those expressed or implied in such forward-looking information.
Readers are cautioned not to place undue reliance on forward-looking information. Minaurum does not intend, and expressly disclaims any intention or obligation to, update or revise any forward-looking information whether as a result of new information, future events or otherwise, except as required by law.
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