Denison Mines Corp. Announces Discovery of Additional High-Grade Mineralization At Gryphon and Reports Results from Successful Delineation Program

Published: 2025-07-16 08:21:27 ET DML.TO

Published on 07/16/2025 at 08:21

Denison Mines Corp. announced the discovery of additional high-grade mineralization approximately 40 metres outside of the previously estimated mineralized domain associated with the D1 lens of the Gryphon uranium deposit ("Gryphon"). The delineation results demonstrate that Gryphon is an excellent high-grade basement-hosted uranium deposit that justifies further project development evaluation and de-risking.

With a focus on confirming the mineralization in the A-series of lenses, a limited number of drill holes were designed to test for possible expansion of the estimated mineral resource. As a result, the company are excited that drill hole WR-837AD2 encountered high-grade mineralization outside of the existing mineralized domain in an area that remains wide open for further expansion down-plunge and along strike. The company is currently developing plans to follow-up this result and test other expansion targets.

Denison reports its initial drilling results as radiometric equivalent uranium ("%eU3O8") from a calibrated, triple gamma, down-hole probe. All mineralized intersections have been sampled for chemical U3O8 assay and final results will be compiled following receipt of the data. Together the B and C series lenses account for approximately 20% of the total estimated Indicated Mineral Resources.

Several drill holes encountered significant results, demonstrating the high-grade nature of Gryphon, including the following results from WR-831D1D2, which tested the primary lenses and returned the best mineralized intercepts from the delineation program: In August 2023, Denison filed a technical report summarizing the results of (i) the feasibility study completed for ISR mining of the high-grade Phoenix uranium deposit and (ii) a cost update to the 2018 Pre-Feasibility Study for conventional underground mining of the basement-hosted Gryphon uranium deposit.