Zacatecas Silver Expands Oso Negro to Over 3 Kilometres of Mapped Gold-Silver Veins; Phase Two Rock Chip Sampling Returns up to 20.3 g/t Gold and 3,480 g/t Silver
VANCOUVER, British Columbia, Sept. 10, 2026 (GLOBE NEWSWIRE) -- Zacatecas Silver Corp. (TSXV: ZAC | OTCQB: ZCTSF | FRA: 7TV) (“Zacatecas Silver” or the “Company”) is pleased to announce assay results from the second phase of rock chip sampling at its Oso Negro project in Sonora, Mexico. Phase Two returned individual grab samples grading up to 20.3 g/t gold and 3,480 g/t silver, extended the mapped vein system to more than 3 kilometres, and confirmed continuous gold-silver mineralization along the full 600 metre strike length of the Prospecto vein. Both the Prospecto and Tere veins are now drill-ready with drill plan designs and permitting underway.
Highlights
- 354 rock chip samples were collected and assayed in Phase Two, bringing the total to 510 samples across the two programs completed to date.
- 63 Phase Two samples assayed between 1 g/t and 20.3 g/t gold, and 58 samples assayed between 100 g/t and 3,480 g/t silver. 20 samples returned over 1% lead or zinc.
- Mapped vein strike length has been extended to over 3 kilometres, up from the 2 kilometres reported after Phase One, with new vein extensions identified at both the Prospecto and Tere systems.
- The Prospecto vein and its southeast splays are gold-silver mineralized along their entire 600 metre mapped strike length.
- Veins are up to 3 metres wide, multiphase, and carry textures and geochemical signatures typical of the uppermost levels of a low sulphidation epithermal system — indicating that the boiling zone, which hosts the highest precious metal grades in these systems, may be preserved at depth.
- Prospecto and Tere are drill-ready. The Company will provide an update on the planned diamond drill program shortly.
Sampling Program
A total of 156 rock chip samples were collected during Phase One (see news release dated July 9, 2026), of which 134 were vein samples. A further 354 rock chip samples were collected and submitted for assay during Phase Two, which was completed in the first week of July 2026. All samples were cut for reference, photographed and dispatched to ALS for gold, silver and base metal analysis.
Of the 134 vein samples collected in Phase One, 39 assayed between 1 g/t and 14.8 g/t gold, 35 assayed between 100 g/t and 2,340 g/t silver, and 11 assayed over 1% combined lead and zinc. Of the 354 samples assayed in Phase Two, 63 assayed between 1 g/t and 20.3 g/t gold, 58 assayed between 100 g/t and 3,480 g/t silver, and 20 assayed over 1% lead or zinc. Phase Two therefore returned both a higher number and a higher tenor of anomalous gold and silver samples than Phase One.
Geology and Results
Geological mapping during Phase Two identified additional vein extensions at both the Prospecto and Tere vein systems (Figures 1 and 2), and the Company has now mapped over 3 kilometres of veins. Veins are up to 3 metres wide and multiphase, with common vein breccias and pervasive iron oxides after sulphides. Vein textures and geochemical signatures are consistent with the uppermost levels of a low sulphidation epithermal system, which suggests that the boiling zone and associated precious metal mineralization may be preserved at depth.
Gold and silver assays confirm that the Prospecto vein and its splays to the southeast are strongly gold-silver mineralized along the entire 600 metre mapped strike length (Figures 1 and 2).
Both the Prospecto and the Tere veins are drill-ready and the Company will provide an update on the planned diamond drill program shortly. The high-grade gold and silver assays returned from outcropping rock chip samples define robust exploration targets that can be tested initially with shallow, angled diamond drill holes.
Figure 1: Oso Negro Phase One and Two Combined Rock Chip Sample Locations and Silver Grade Map
Figure 2: Oso Negro Phase One and Two Combined Rock Chip Sample Locations and Gold Grade Map
CEO Quote
"Phase Two did two things for us at Oso Negro - it extended the system to over three kilometres of mapped veins, and it confirmed the Prospecto Vein carries gold and silver along its entire 600-metre strike, " said Eric Vanderleeuw, Chief Executive Officer and Director. "This is an undrilled system showing the surface signature of a preserved low sulphidation target, and Prospecto and Tere are where we want to start. With Cumaro advancing alongside it, Sonora is becoming a significant part of our story, and with our recent financing we have the means to advance it. "
Analytical Methods and QA/QC
Rock chip samples were collected and bagged under the supervision of Company personnel following standard industry practices. Samples were submitted to ALS Zacatecas for analysis. Samples were prepared by drying, sieving and pulverizing, and analyzed for Ag and a suite of elements by multi-element ICP methods following four-acid digestion. The Company inserted certified reference materials, blanks and field duplicates into the sample stream to monitor analytical quality.
Qualified Person
The technical information in this news release has been reviewed and approved by Chris Wilson, B.Sc. (Hons), PhD, FAusIMM (CP), FSEG, FGS, Chief Geologist of Zacatecas Silver. Dr. Wilson is a Qualified Person as defined by NI 43-101 and is not independent due being Chief Geologist and a director.
About Zacatecas Silver Corp.
Zacatecas Silver is a multi-asset precious metals exploration company with a portfolio of six projects across Mexico, spanning Zacatecas, Sonora, Morelos, and Oaxaca.
The Zacatecas Silver Project is located in Zacatecas State, within the highly prospective Fresnillo silver belt, which has produced over 6.2 billion ounces of silver. The Company holds 7,826 hectares of ground prospective for low-sulphidation and intermediate-sulphidation silver-base metal mineralization. A Mineral Resource Estimate at the Panuco deposit comprises 3.41 million tonnes at 187 g/t AgEq for 20.5 million ounces AgEq (see news release dated May 31, 2023). The property is 25 km southeast of MAG Silver 's Juanicipio Mine and Fresnillo PLC 's Fresnillo Mine, and shares boundaries with Defiance Silver and Endeavour Silver.
Esperanza is an advanced stage, attractive low-cost, low-capital-intensity and low-technical-risk growth project located in Morelos state, Mexico. The Company announced a Mineral Resource Estimate at Esperanza consisting of a Measured and Indicated Mineral Resource Estimate of 45.4 million tonnes at 0.79 g/t AuEq (0.76 g/t gold and 8.5 g/t silver) for 1.15 million ounces AuEq (1.11 million ounces gold and 12.37 million ounces silver) and an Inferred Mineral Resource Estimate of 11.2 million tonnes at 0.57 g/t AuEq (0.53 g/t gold and 11.2 g/t silver) for 208 thousand ounces AuEq (190 thousand ounces gold and 4.02 million ounces silver) (see news release dated June 22, 2026).
The Company also holds four exploration properties in Sonora and Oaxaca. Oso Negro (Sonora) is an undrilled, high-grade low sulphidation epithermal system with multiple veins mapped over more than 3 km of strike length. Cumaro (Sonora) is situated along trend from Coeur Mining’s El Picacho development and hosts extensions of proven low sulphidation vein systems with high-grade channel sampling results. La Lola (Sonora) is a large, underexplored 1,183-hectare property anchored by the La Barra vein, a 5 km structure reaching up to 40 m in width. Ejutla (Oaxaca) comprises 10,603 hectares in the Taviche-Miahuatlán region near the former Fortuna Silver San José Mine, hosting multiple vein systems and alteration zones anomalous in gold, silver, and Carlin-style pathfinder elements.
On behalf of the Company
Eric Vanderleeuw
Chief Executive Officer and Director
(519) 729 2440
Forward-Looking Statements
Information set forth in this news release contains forward-looking statements that are based on assumptions as of the date of this news release. These statements reflect management’s current estimates, beliefs, intentions and expectations. They are not guarantees of future performance. Zacatecas Silver cautions that all forward-looking statements are inherently uncertain and that actual performance may be affected by many material factors, many of which are beyond their respective control. Such factors include, among other things: risks and uncertainties relating to Zacatecas Silver’s limited operating history, its proposed exploration and development activities on Zacatecas Properties and the need to comply with environmental and governmental regulations. Accordingly, actual and future events, conditions and results may differ materially from the estimates, beliefs, intentions and expectations expressed or implied in the forward-looking information. Except as required under applicable securities legislation, Zacatecas Silver does not undertake to publicly update or revise forward-looking information.
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the Exchange) accepts responsibility for the adequacy or accuracy of this release.
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