Transatlantic Samples 36.1% Cu over 2.6 metres at Monitor Project - Big Elk Prospect

Vancouver, British Columbia--(Newsfile Corp. - July 14, 2025) - Transatlantic Mining Corp. (TSXV: TCO) (the "Company") is pleased to provide an update on its exploration activities at the Big Elk and Anvil prospects, key targets within the larger Monitor Copper-Gold Project. The project is located approximately 8 kilometers south of Taft, Idaho, USA and continues to demonstrate prospectivity.

Highlights of the Exploration Program:

• High-Grade Surface Samples at Big Elk: An outcrop sample returned 36.1% copper (Cu) over 2.6 metres, with another gossanous sample yielding 6.6% Cu, confirming significant mineralization.

• Drilling Validates Targeting: Initial 1,100 metres of drilling confirmed the geometry of known mineralized structures, including intersecting historical workings, which provides critical insights for future targeting.

• Anvil Prospect Potential: Recent underground samples at Anvil indicate multiple copper fissure veins within a complex system.

"We are very pleased with the successful outcomes of our exploration at Big Elk, which has confirmed our geological understanding and the presence of copper mineralization," said Bernie Sostak, CEO of Transatlantic Mining. "Our initial magnetic survey results and new Lidar data are providing compelling insights, supporting delineation of fissure veins and offering a clearer picture of the historical workings. This comprehensive information, covering both Big Elk and Anvil, is actively being integrated into an updated NI 43-101 report for the Monitor Project, positioning us strongly for our next targeted drill campaign and the discovery of additional veins within the claim package."

Webinar:

Transatlantic CEO Bernie Sostak will host an interactive webinar discussing the company's exploration programs and future plans on Wednesday, July 16, 2025, at 9:am PT. Register in advance for this meeting via the following link:

https://us02web.zoom.us/meeting/register/HGAW8MmQSpqph3pg-hcw1Q

Geology and Mineralization

At the Big Elk prospect, copper mineralization is found within steeply dipping fissure veins that form along second-order structures within a prominent shear zone, trending approximately N40W to N70W. These veins, typically up to 1.8 metres wide, are characteristic of the broader Coeur d'Alene mining district. In this eastern and southeastern part of the district, where the Monitor Project is situated, veins are typically copper-rich with reduced silver, lead, and zinc content, suggesting formation under higher-temperature conditions or closer proximity to the hydrothermal source. These copper-rich veins are generally less than 5 meters wide, extend to significant depths, and primarily contain chalcopyrite, pyrite, calcite, siderite, and quartz. Hydrothermal alteration, notably pervasive siderite zoning and bleaching, is a defining characteristic of the mineralized zones, with disseminated siderite sometimes extending hundreds of meters into the wall rocks.

Exploration Results

Building on this geological understanding, the Company conducted a systematic exploration program, implementing industry best practices to confirm the property's geological and mineralogical characteristics.

Initial surface sampling at the Big Elk prospect yielded encouraging copper results. An outcrop sample excavated next to a historic shaft returned 36.1% Cu over 2.6 metres (see Figure 1). Further surface assessment included a surface sample of gossanous copper with iron in the stockpile, which assayed 6.6% Cu. ( *See also historical reports)

Figure 1: High-grade copper showing from the Big Elk Prospect at Transatlantic Mining's Monitor Project. 

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The initial drill program at Big Elk comprised fourteen holes totaling 1,100 metres, designed to test copper anomalism found on earlier surface geological reconnaissance and further confirm the orientation of the mineralized system. Hole depths ranged from 21 metres to 111 metres in 14 holes. Ten of these holes intersected voids where historical mining had taken place, providing valuable insights into the geometry and continuity of the veins. While the drilling did not intersect new vein material to yield positive analytical results, it successfully confirmed the geometry (strike and dip) of the vein system mined along the Big Elk workings, providing essential data for the planning of subsequent drilling campaigns (Figures 2 and 3). Four exploration holes did not encounter visible mineralization and were not sampled. There are no historical mine plans at the Big Elk prospect, and the drilling was targeting the uncovered subcrop to determine extensions along strike and down dip. All samples collected were subsequently sent to Christofferson Labs, LLC. in Smelterville, Idaho, USA for analysis of gold and then to American Analytical Laboratories in Osburn, Idaho for an ICP analysis.

Figure 2: Map of the Big Elk Prospect, a subset of the Monitor Project 

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Figure 3: Map of the Big Elk Prospect, a subset of the Monitor Project (Table 1,2)

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Overall, the Company's exploration efforts confirmed the strike and dip of the vein mined along the Big Elk workings. Surface samples indicate the veins contain copper mineralization. Furthermore, through mapping and sampling of the Anvil working, the Company has identified additional veins within the claim block. Both the Big Elk and Anvil prospects represent historical workings on fissure veins within the larger shear zone, confirming the presence of multiple veins within the shear zone that encompasses the entire project.

Sampling, Analysis, and Quality Assurance/Quality Control (QA/QC)

All samples, including those from surface across the Big Elk Vein subcrop and remnant copper mineralization in the outlying dump area (Table 1), as well as drilling, were sent to Christofferson Labs, LLC in Smelterville, Idaho, USA for gold analysis. Subsequent ICP analysis was performed at American Analytical Laboratories in Osburn, ID. All drilling and sampling results for the Big Elk prospect are detailed in Table 2. All analytical procedures adhered to industry-standard protocols, and results have passed internal QA/QC checks.

Table 1: Surface Sampling across subcrop Big Elk Vein

Table 2: Drill hole summary from Big Elk drilling

See also,

*NI43-101 :Copper-Gold-Silver Mineralization at the Monitor Mine Property, Eastern Coeur d'Alene Mining District, Shoshone County, Idaho, USA.,( Ray July 2013) and

* New Release May 1, 2017

About the Monitor Claim Group:

Transatlantic Mining has numerous prospects within the greater Monitor Copper-Gold Project. At the historical Monitor mine, historical grades of up to 15% Copper and 8 g/t Gold were achieved. Surface samples of other prospects have returned grades of up to 30% copper, which have been reported previously.

Qualified Person Review:

The technical information contained in this news release has been reviewed and approved by Zachary J. Black, SME-RM, a Principal for Ethos Geological Inc., who is a Qualified Person pursuant to National Instrument 43-101.

About Transatlantic Mining Corp.

Transatlantic Mining (TSXV: TCO) is an emerging precious and base metal explorer. The Company has a focus on converting projects into mines within stable mining jurisdictions. The Company currently holds property interests including an 80% Joint Venture position on the Monitor Copper-Gold project in Montana-Idaho (USA) and 100% of the Golden Jubilee Gold Project with its associated mining rights. The Company also has an extended lease, right to mine, and purchase arrangement for the Miller Gold Mine in Montana, moving towards 100% ownership by way of a payment royalty.

Cautionary Statement Regarding Forward-Looking Statements

This news release contains "forward-looking statements" within the meaning of Canadian securities legislation. These forward-looking statements include, but are not limited to, statements regarding the Company's future exploration plans, geophysical programs, and the potential for mineralization. Forward-looking statements are subject to known and unknown risks, uncertainties, and other factors that may cause the actual results, level of activity, performance, or achievements of the Company to be materially different from those expressed or implied by such forward-looking statements. These factors include, but are not limited to, risks associated with the exploration and development of mineral properties, the Company's ability to obtain necessary permits, and the availability of financing. Readers are cautioned not to place undue reliance on forward-looking statements. The Company undertakes no obligation to update or revise any forward-looking statements, except as required by law.

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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