Cosa Commences 3,000 Metre Summer Drilling Program At The Murphy Lake North Uranium Project

(MENAFN- Newsfile Corp) Vancouver, British Columbia--(Newsfile Corp. - June 25, 2025) - Cosa Resources Corp. (TSXV: COSA) (OTCQB: COSAF) (FSE: SSKU) (" Cosa " or the " Company ") is pleased to report commencement of a 3,000-metre summer drilling program targeting the Hurricane and Cyclone trends on the Murphy Lake North Project (" MLN " or the " Project "). MLN is a joint venture (the " Joint Venture ") between Cosa and Denison Mines Corp. (" Denison ") ( TSX: DML ) ( NYSE American: DNN ) and is located in the eastern Athabasca Basin, Saskatchewan. Cosa is the project operator and holds a 70% interest with Denison holding a 30% interest.

Highlights

• Denison, Cosa's Joint Venture partner and largest shareholder, has indicated it will fund its portion to retain a 30% interest in the Murphy Lake North Joint Venture
• Largest drill program to date on the Project with a planned 3,000m in up to eight drill holes
• Drilling is planned to follow up significant sandstone alteration intersected by winter drilling at the Hurricane trend and to complete reconnaissance testing of the parallel Cyclone trend

Keith Bodnarchuk, President and CEO of Cosa, commented: "This is the most exciting time of the year for Cosa as drilling has officially begun. Thanks to our VP Exploration, Andy Carmichael, and the rest of our technical team and contractors for ensuring a safe and timely start to this summer drilling program. We are eager to continue testing promising targets at the Hurricane and Cyclone trends following the encouraging results of our inaugural winter program earlier this year. With positive sentiment returning to the uranium sector and the continued support of our Joint Venture partner and largest shareholder, Denison, we are well-positioned to advance the Murphy Lake North Project toward its full potential."

Murphy Lake North

Murphy Lake North covers a portion of the Larocque Lake trend and is located 2.7 kilometres east of the Hurricane deposit (Figures 1 & 2). Hurricane is the world's highest-grade Indicated Uranium Resource and was discovered and delineated for IsoEnergy Ltd. by current members of Cosa's management, board of directors, and advisors from 2018 through 2022. The Larocque Lake trend also hosts the high-grade Larocque Lake Zone, Yelka Prospect, and Alligator Lake Zone.

Initial drilling in winter 2025 confirmed that up to two kilometres of Hurricane trend basement geology is present within the Project (See Cosa news release dated March 20, 2025). While testing the southern portion of the Hurricane trend, the fourth and final drill hole of the program intersected a broad zone of alteration and structure in the lower sandstone that is open along strike in both directions.

Per the completed Acquisition Agreement between Cosa and Denison (see Cosa's news release dated January 14, 2025), Cosa expects to meet its obligation to sole-fund C$1.5 million of exploration expenditures at the Project during the summer drill program. Denison has indicated that it intends to fund its share of exploration costs that exceed Cosa's sole-funding obligation in order to retain its 30% interest in the Project.

For details of Cosa's planned drill program and target areas, see the Company's news release dated 17 June 2025.

Figure 1 - Cosa's Eastern Athabasca Uranium Projects with Joint Venture Projects

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Figure 2 - Murphy Lake North Drilling Results and Conductive Trends

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About Cosa Resources Corp.

Cosa Resources is a Canadian uranium exploration company operating in northern Saskatchewan. The portfolio comprises roughly 237,000 ha across multiple underexplored 100% owned and Cosa-operated Joint Venture projects in the Athabasca Basin region, the majority of which reside within or adjacent to established uranium corridors.

In January of 2025, the Company entered a transformative strategic collaboration with Denison that has secured Cosa access into several additional highly prospective eastern Athabasca uranium exploration projects. As Cosa's largest shareholder, Denison gains exposure to Cosa's potential for exploration success and its pipeline of uranium projects.

Cosa's award-winning management team has a long track record of success in Saskatchewan. In 2022, members of the Cosa team were awarded the AME Colin Spence Award for their previous involvement in discovering IsoEnergy's Hurricane deposit. Prior to Hurricane, Cosa personnel led teams or had integral roles in the discovery of Denison's Gryphon deposit and 92 Energy's GMZ zone and held key roles in the founding of both NexGen and IsoEnergy.

The Company's core focus throughout 2025 is drilling at the Murphy Lake North Joint Venture. Murphy Lake North is a 70/30 Joint Venture between Cosa and Denison respectively and is located at the northern end of the Larocque Lake trend. The Project is within three kilometres of and on trend with the Hurricane deposit. Initial drilling completed by Cosa during winter 2025 intersected broad zones of hydrothermal alteration of the sandstone, associated with prospective basement structures interpreted as the strike extension of those controlling the Hurricane deposit. An expanded follow up campaign is currently in planning for the summer season.

Technical Disclosure

Historical drilling and geophysical results for Murphy Lake North and adjacent projects were sourced from the Saskatchewan Mineral Assessment Database (SMAD). SMAD sources for the Murphy Lake North Project include file numbers 74I-0060, 74I09-0057, 74I09-0064, 74I09-0066, 74I09-0077, 74I09-0098, and MAW00510. Data and reports related to the 2020 ground EM survey completed by Denison are not presently available via SMAD and were supplied to Cosa by Denison.

SMAD sources for drilling and geophysical results proximal to Murphy Lake North include 64L05-0161, 64L05-0180, 74I-0066, 74I-0067, 74I01-0114, 74I08-0056, 74I09-0053, 74I09-0061, 74I09-0064, 74I09-0071, 74I09-0079, 74I09-0087, 74I09-0088, 74I09-0090, 74I09-0091, 74I09-0092, MAW01939, MAW02327, MAW02599, and MAW02395.

Drill hole collar locations for Murphy Lake North and relevant along-strike drill holes were verified from air photos. The collar locations of Murphy Lake North drill holes CRK-144 and CRK-145 were verified on the ground using a handheld GPS and determined to be within 20 metres of the locations derived from air photos. Segments of drill core from CRK-143 and CRK-144 were reviewed in the field; further review was hampered by the deteriorated condition of core boxes.

Verification of historical geophysical results included confirming the locations of geophysical survey grids from air photos, compiling data from geophysical surveys completed post year 2000, engaging a consultant to re-interpret historical geophysical surveys completed inside MLN and comparing to historical interpretations, and evaluating whether interpreted geophysical results could be reasonably explained by historical drilling results.

Qualified Person

The Company's disclosure of technical or scientific information in this press release has been reviewed and approved by Andy Carmichael, P.Geo., Vice President, Exploration for Cosa. Mr. Carmichael is a Qualified Person as defined under the terms of National Instrument 43-101. This news release refers to neighbouring properties in which the Company has no interest. Mineralization on those neighbouring properties does not necessarily indicate mineralization on the Company's properties.

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