Radisson Mining Resources Inc. reported an updated Mineral Resource Estimate at its 100%-owned O'Brien Gold Project located in the Abitibi region of Quebec. The Company is currently undertaking a fully-funded 140,000-metre step-out drill program at the Project with the objective of determining the scope of mineralization to a depth of 2 kilometres. This program commenced in 2025 and is expected to continue through the first half of 2027.
The updated MRE is an interim report that demonstrates the impact of recent drilling successes completed as of December 31, 2025. Highlights include: 82% increase in Inferred Mineral Resources from step-out drilling intersecting new mineralization, with 1.69 million ounces (Moz) in 10.37 million tonnes (Mt) at 5.08 grams per tonne (g/t) gold (Au); 8% increase in Indicated Mineral Resources with 0.63 Moz in 3.49 Mt at 5.59 g/t Au; Estimated using US$2,500/oz Au and 2.2 g/t Au cut-off, with a refined geological model and capping strategy, establishing the go-forward basis for future, modern mine development. Mineral Resource Estimate (effective January 31, 2026): The MRE is based on 428,440 metres of drilling completed to the end of December 31, 2025, and has been authored by SLR Consulting (Canada) Ltd. (SLR).
The estimate utilizes a 2.2 g/t Au cut-off at USD 2,500/oz and makes certain assumptions on mining and processing costs, currency exchange rate, and metallurgical recovery. A wireframe vein model prepared by Radisson and reviewed by SLR constrains the estimate and applies a minimum width of 1.2 metres. Individual assays are capped at 60 g/t Au prior to compositing to full width of the veins, and the block model utilizes 5 by 2 by 5 metre blocks consistent with recent mine design studies.
An MRE for the Project was previously published in March 2023 based on 325,509 metres of drilling completed to the end of 2022. Indicated Mineral Resources (effective March 2, 2023) were estimated at 0.50 Moz (1.52 Mt at 10.26 g/t Au) with additional Inferred Mineral Resources of 0.45 Moz (1.60 Mt at 8.66 g/t Au). The 2023 study applied a 4.5 g/t Au cut-off at USD 1,600/oz Au.
In July 2025, Radisson published a Preliminary Economic Assessment (PEA) for the Project that utilized the 2023 estimate re-blocked by SLR in the Z-direction from 10 metres to 5 metres to allow for more flexible underground mine design. A cut-off of 2.2 g/t Au at US$2,000/oz Au and an updated set of economic criteria were applied in the re-blocking exercise consistent with the parameters used for the optimization of the PEA's underground mine schedule. No other changes were made.
Indicated Mineral Resources (effective May 6, 2025) were estimated at 0.58 Moz (2.20 Mt at 8.22 g/t Au) with additional Inferred Mineral Resources of 0.93 Moz (6.67 Mt at 4.35 g/t Au). The updated MRE released benefits from 66,387 metres of additional drilling in 122 drill holes conducted between 2023 and 2025, which is the most significant factor in the increase of Inferred Mineral Resources. Radisson has also validated an additional 36,544 meters of historic drilling.
The updated MRE utilizes similar estimation parameters to previously, but a more restrictive approach to capping. In the March 2023 estimate, and as incorporated in the re-blocked May 2025 estimate, capping at 40 g/t Au was applied to the full-length composites. In the updated MRE, capping has been applied at 60 g/t Au to the underlying assays prior to compositing.
This has the effect of reducing the average grade by approximately 12%, and in the opinion of Radisson and SLR is an appropriate approach to a narrow high-grade vein deposit such as O'Brien.
