Vancouver, British Columbia--(Newsfile Corp. - December 1, 2025) - Transatlantic Mining Corp. (TSXV: TCO) (the "Company") is pleased to announce the completion and filing of its maiden NI 43-101 technical report for the Monitor Copper Project, an 80%-owned joint venture property located in Shoshone County, Idaho and Mineral County, Montana.

Highlights:

• Initial NI 43-101 technical report establishes Exploration Targets for three copper siderite vein systems.
• 2015 drilling by Transatlantic confirmed copper, silver, and gold mineralization with intercepts up to 1.87% Cu over 0.8m and 71.5 g/t Ag over 0.3
• Grab samples near Monitor shaft returned 57.7 g/t Ag, 15.4 g/t Au, and >1% Cu
• Combined Exploration Target ranges from 1,200,000 to 2,900,000 tonnes with grades of 1.2-3.5% copper, with further potential for silver and gold credits. Historical mined grades are well in excess of the Combined Exploration Target.
  The potential quantity and grade of the Exploration Target are conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource and it is uncertain if further exploration will result in the estimation of a Mineral Resource.
• Project located in the Coeur d'Alene Mining District with road access
• Phased development strategy prioritizes underground drilling with the option of bulk sampling over the more expensive surface drilling
• St. Lawrence tunnel confirmed structurally sound for 120 meters, enabling a cost-effective underground exploration platform

"We're extremely pleased with this maiden technical report. Our surface sampling and drilling has confirmed attractive copper grades with precious metal credits on the property. This leads into the next phase plan to access into historical underground workings, enabling more cost-effective drill sampling and the option for a bulk mine sample," said Bernie Sostak, CEO of Transatlantic Mining Corp. "Rather than spending heavily on surface drilling in the mountain terrain, we're leveraging on underground access to efficiently evaluate the deposit through drilling from underground access. This approach de-risks the project while providing valuable metallurgical data."

Exploration Target

The technical report, prepared by Ethos Geological, represents the Company's first NI 43-101 report for the Monitor Project and details the potential of three exploration targets on the property: the Monitor, Richmond, and Big Elk copper siderite vein systems. These steeply-dipping fissure veins exhibit characteristics consistent with known copper veins throughout the Coeur d'Alene Mining District.

The potential quantity and grade of the Exploration Target are conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource and it is uncertain if further exploration will result in the estimation of a Mineral Resource.

Table 1: Exploration Target Summary

The Exploration Target is based on mapped structure lengths from surface workings and historical reports (Monitor: 488m, Richmond: 1,158m, Big Elk: 305m), documented vein widths from the 1923 Hershey and Umpleby geological reports, and down-dip extensions to 550 meters vertical depth. Historical mining reached approximately 180 meters depth before operations ceased in the 1920s. Grade ranges are scaled down from historical production grades to reflect broader zones of mineralization. Vein widths range from 1.2 to 4.6 meters based on historical reports. The exploration target assumes discontinuous mineralization along mapped vein structures, consistent with copper-siderite vein systems elsewhere in the district.

Project Location and Infrastructure

The Monitor Project is located in the Coeur d'Alene Mining District, where mining has been conducted continuously since the 1880s to early 1900's. The great fire of the 1910's damaged major infrastructure at that time. The project has road access and is situated in a region with experienced mining contractors and infrastructure to support exploration and potential future operations.

Strategic Development Approach

Transatlantic has developed a phased exploration strategy that prioritizes cost-effective underground evaluation over expensive surface drilling in mountainous terrain. The Company's 2015 assessment confirmed the St. Lawrence tunnel remains structurally sound in part to 120 meters, providing direct access to drill the undrilled Monitor vein systems at depth.

Three-Phase Exploration Program:

Phase 1 - Underground Exploration: Rehabilitation of existing underground workings, systematic channel sampling and mapping, underground drilling, and an option for the collection of a 10,000-tonne bulk metallurgical sample. This phase will provide high-quality geological data while generating material for comprehensive metallurgical testing.

Phase 2 - Property-Scale Surveys: Detailed geological mapping, geophysical surveys (magnetic and IP/resistivity), and petrophysical analysis to identify additional targets and refine the geological model.

Phase 3 - Targeted Surface Drilling: Surface drill programs will be designed based on underground results, focusing on down-plunge extensions and potential stratiform mineralization in the underlying Revett Formation.

Exploration by Transatlantic (2013-2024)

Table 2: Completed Exploration Activities

Next Steps

The Company is advancing permitting for underground rehabilitation and underground drill planning. Management will provide updates as milestones are achieved.

Qualified Person

The technical information in this news release has been reviewed and approved by Zachary J. Black, SME-RM, Ethos Geological as an Independant Qualified Person as defined under NI 43-101

About Transatlantic Mining Corp.

Transatlantic Mining Corp. (TSXV: TCO) is a precious and base metals explorer focused on advancing projects toward production in established mining jurisdictions. The Company holds an 80% interest in the Monitor Copper Project (Idaho/Montana), 100% of the Golden Jubilee Gold Project, and rights to the Miller Gold Mine in Montana. The Company emphasizes cost-effective exploration strategies and partnerships that align with its development-focused approach.

Cautionary Statement Regarding Forward-Looking Information

This news release contains forward-looking statements within the meaning of applicable securities legislation. Forward-looking statements relate to future events or future performance and reflect Company management's expectations or beliefs regarding future events including the potential for mineralization, future exploration programs, timing of exploration activities, and the ability to obtain financing. These statements are based on assumptions and involve risks and uncertainties. Actual results may differ materially from those anticipated in these forward-looking statements due to various factors including changes in economic conditions, regulatory changes, and availability of financing. The Company undertakes no obligation to update forward-looking statements except as required by applicable securities laws.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

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