Mineros Reports Initial Mineral Resource Estimate for Guillermina Deposit in Nicaragua

• Initial mineral resource estimate completed for Guillermina deposit containing gold, silver and zinc located 3km north of Porvenir Project
• Resource incorporates 9,798 metres across 61 diamond drill holes completed between 2011 and August 2024
• Deposit contains 1.8km vein system with hydrothermal breccias and veinlets up to 20 metres thick
• Net smelter return cut-off value established at $82.50 per tonne based on underground mining parameters
• 2025 drilling programme underway with 2,000 metres planned for metallurgical testing and resource upgrading

Mineros S.A. (TSX:MSA) is a Latin American gold mining company headquartered in Medellín, Colombia. The Company has a diversified asset base with mines in Colombia and Nicaragua and a pipeline of development and exploration projects throughout the region. The board of directors and management have extensive experience in mining, corporate development, finance and sustainability. Mineros has operated for almost 50 years with a focus on safety and sustainability at all operations.

Initial Resource Estimate Defined

The Guillermina deposit consists of a polymetallic vein system located approximately four kilometres west of the Pioneer Mine in northeastern Nicaragua. The deposit features a 1.8-kilometre vein system oriented at an azimuth of 245 degrees with anomalies in gold, silver and zinc. The mineralisation system includes hydrothermal breccias, stockwork and veinlets up to 20 metres in thickness, with a crustiform to colloform-banded quartz chalcedony-adularia matrix.

The resource estimate incorporates results from 61 diamond drill holes totalling 9,798 metres completed between 2011 and August 2024. Grades were constrained with three-dimensional wireframes of the principal mineralised vein and interpolated by the inverse distance cubed method into a block model. Parent blocks measure 2 metres by 2 metres by 2 metres with sub-blocks of 1 metre by 1 metre by 1 metre.

Classification of solids was based on drill hole spacing, with distances less than 50 metres classified as Indicated Mineral Resources and distances less than 100 metres classified as Inferred Mineral Resources. The breccia matrix contains galena, sphalerite and hematite occurring in patches and bands throughout.

"We are pleased to have reached this milestone at Guillermina, one of several key targets in our portfolio of organic growth projects," stated David Londoño, President and CEO. "This deposit represents an exciting opportunity that could play an important role in the Porvenir Project's future development."

Exploration History and Drilling Results

Building on drilling results from the Neptuno Company in the 1970s, Hemco carried out a drilling campaign at Guillermina in 2011 and 2012 consisting of 1,070 metres across seven drill holes, revealing zinc anomalies as well as gold and silver anomalies. Recognising the potential for polymetallic mineral production at the Porvenir Project, Mineros initiated a reconnaissance diamond drilling campaign in 2022, completing 887 metres across seven drill holes.

The initial campaign confirmed the depth and continuity of the deposit, delineating a central extension of a mineralised structure hosting galena, sphalerite and chalcopyrite with thicknesses ranging from two metres to 15 metres. Following these results, drilling efforts in 2023 focused on confirming the extensions of mineralisation, with 11 holes drilled for a total of 1,898 metres.

By 2024, the campaign advanced to infill drilling to improve the definition of mineralisation, with 6,498 metres drilled across 40 holes. The core of the mineralised vein was drilled at approximately 50-metre spacing. Diamond drill core samples are selected by geologists on site with sample intervals typically one metre in length. All samples undergo quality assurance and quality control procedures aligned with industry practices.

Resource Modelling Parameters

A net smelter return (NSR) value was assigned to blocks to validate the geological interpretation and for resource reporting. NSR represents the estimated dollar value per tonne of mineralised material after accounting for smelter terms, including revenues, treatment and refining charges, penalties, smelter losses, transportation and sales charges. The NSR calculation is based on metallurgical testing at the Porvenir Project using comparable smelter terms.

Metallurgical recovery assumptions include gold recovery rates from 85% to 95% depending on grade, silver recovery from 75% to 85%, and zinc recovery from 85% to 95% based on concentrate grades. Metal price assumptions used in calculations include gold at $1,650 per ounce, silver at $20 per ounce and zinc at $1.20 per pound. Standard smelting and refining charges were applied to concentrates with the assumption that concentrates would be marketed internationally.

A bench and fill mining method was evaluated for Guillermina applying parameters used for the Porvenir Project. Total unit operating cost included mining, processing, power and general administrative expenses, resulting in total operating cost of approximately $82.50 per tonne of mineralised material. Mineral Resources are constrained within underground reporting shapes using a minimum mining width of one metre and the NSR cut-off value of $82.50 per tonne.

2025 Development Programme

The 2025 drilling campaign at Guillermina commenced in July 2025 with 2,000 metres planned. This programme is designed to collect representative samples for metallurgical testing consistent with parameters established for the Porvenir Project and will serve as infill drilling to upgrade Inferred Mineral Resources to Indicated Mineral Resources. Mineros has commenced evaluating potential mining methods and is exploring synergies with the Porvenir Project to support potential expansion of the overall mineral resource inventory.

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