Denison Mines Corp.

The MLJV's producing deposit, mined by the joint venture's patented SABRE surface-access borehole method. A high-pressure water jet is lowered through a sub-half-metre borehole to erode the mineralised horizon, creating cavities up to four metres in diameter; cuttings are lifted to surface as a slurry and screened, and each mined cavity is backfilled with a cemented mixture. Commercial mining restarted in July 2025 after a 2021 field test recovered approximately 1,500 tonnes of ore grading 4% to 11% U3O8. The resource estimate is supported by the January 2007 McClean North Technical Report and has not been re-estimated for the mining that commenced in 2025, so it does not reflect depletion.

Surface stockpile of mined ore at the McClean Lake site, carried as a proven mineral reserve. The estimate was prepared from the year-end stockpile survey reported by Orano Canada, the MLJV operator, rather than from a technical report. It is the only proven reserve Denison holds outside Phoenix.

Basement-hosted uranium deposit approximately 3 km northwest of Phoenix at Wheeler River, planned as an underground mine. Access is via two blind-bored shafts - a production shaft for personnel, supplies, ore and waste hoisting and fresh air, and a dedicated ventilation and secondary-egress shaft - with a composite steel/concrete liner grouted into basement rock. The mine is divided into five blocks (E Zone, Lower D, Upper and Lower Main, Upper SW), each mined bottom-up by longhole methods, producing approximately 605 t/d of ore and 330 t/d of waste at steady state. Ore is hoisted and trucked to the McClean Lake mill; a two-year ramp-up to a full production rate of 9 million lb U3O8 per year is planned. Processing at McClean Lake requires a toll milling agreement that is not yet established and regulatory approvals not yet obtained, plus certain mill modifications. The Gryphon PFS Update reports a pre-tax IRR of 41.4% and after-tax IRR of 37.6% with a 22-month after-tax payback.

High-grade unconformity-hosted uranium deposit at Wheeler River, planned as an in-situ recovery operation - the first ISR uranium mine in Canada. The 2023 Phoenix feasibility study established a 10-year mine life on proven and probable reserves of 56.7 million lb U3O8 (219,000 tonnes at 11.7% U3O8) with a base case pre-tax IRR of 105.9% and adjusted after-tax IRR of 90.0%. The Zone A high-grade domain is estimated to contain 56.3 million lb U3O8 in measured and indicated resources at an average grade of 46.0% U3O8. Uranium-bearing solution from the wellfield feeds an adjacent self-contained processing plant. A January 2026 capital update raised total initial capital to about $700 million - roughly $100 million pre-FID and $600 million post-FID - at AACE Class 2 precision, with the post-FID IRR at 73%. Grid power arrived in January 2026 and the CNSC approved the environmental assessment and issued the Licence to Prepare a Site and Construct in February 2026, the first Canadian uranium mine approved for construction in over 20 years. FID had not been taken at the reporting date.

The higher-grade of the two Midwest deposits and the subject of the August 2025 Preliminary Economic Assessment assessing in-situ recovery mining, which the AIF describes as a technically sound and economically robust means of extracting significant production with low initial capital costs, a high rate of return and rapid payback. Resources were estimated at a 0.10% U3O8 (0.085% U) cut-off grade. Planned 2026 work includes a feasibility-level assessment of the SABRE mining method alongside the ISR case.

Tthe Heldeth Túé deposit, formerly J Zone, on the Waterbury Lake property, supported by a Preliminary Economic Assessment effective October 30, 2020. The indicated resource was estimated at a 0.10% U3O8 cut-off grade. It is Denison's largest resource outside Wheeler River on a Denison-share basis, at 9,000 thousand pounds U3O8. No mining method is stated for this deposit in the AIF.

The second Midwest deposit, a lower-grade indicated resource with a small but very high-grade inferred component averaging 5.8% U3O8. Resources were estimated at a 0.10% U3O8 (0.085% U) cut-off grade and are supported by the August 2025 Midwest Property PEA. No mining method is stated for this deposit in the AIF.

Uranium deposit on the McClean Lake property supported by the Sue D Report dated March 31, 2006. Indicated and inferred resources were both estimated at a 0.10% U3O8 cut-off grade. Denison's share of the inferred resource rounds to nil. No mining method is stated for this deposit in the AIF.

Uranium deposit on the McClean Lake property, formerly known as Caribou, supported by the 2005 McClean Technical Report. The indicated resource was estimated at a 0.10% U3O8 cut-off grade. No mining method is stated for this deposit in the AIF, so no extraction type is assigned.

Uranium deposit on the McClean Lake property supported by the 2005 McClean Technical Report, with the inferred resource estimated at a 0.10% U3O8 cut-off. The operator conducted confirmatory drilling on a portion of the Sue E resource outside the designated pit and in late 2006 submitted a preliminary analysis detailing an inferred resource of approximately 2 million pounds on a 100% basis in that area, against the 7.3 million pounds in the February 2006 technical report. The resource has not been re-estimated using the newer drill information.

Denison's flagship project, 95%-owned and Denison-operated, comprising 19 contiguous mineral claims over 11,720 hectares in the eastern Athabasca Basin about 600 km north of Saskatoon and 35 km northeast of the Key Lake mill along Highway 914. It hosts the Phoenix ISR deposit and, about 3 km northwest, the Gryphon underground deposit. The property lies within Treaty 10, English River First Nation traditional territory and the Métis homeland, and is covered by impact-benefit type agreements signed with ERFN (2023), KML and Pinehouse (2024) and the Métis Parties and YNLR/Athabasca Communities (2025). Wheeler River is subject to Saskatchewan Crown mineral royalties and a 10% net profits interest held by the WRJV in proportion to participant interests, of which Denison is also a beneficiary; there are no back-in rights or third-party royalties.

25.17%-held JV in the eastern Athabasca Basin operated by Orano Canada, hosting the Midwest Main and Midwest A deposits. The site is under care and maintenance within the Orano-operated McClean and Midwest CNSC licence. In August 2025 Denison reported a Preliminary Economic Assessment for the MWJV assessing ISR mining of the high-grade Midwest Main deposit, which the AIF describes as technically sound and economically robust with low initial capital costs, a high rate of return and rapid payback; the AIF does not publish the PEA's NPV, IRR, capital or operating cost figures. Planned 2026 work includes a feasibility-level SABRE assessment, environmental studies, an EA update and a CNSC licence amendment permitting receipt of Midwest ore. Neither published Midwest subtotal reconciles to its two deposit rows: indicated shows 50,700 klb against 49,500 klb summed and inferred 18,200 klb against 19,400 klb, an offsetting 1,200 klb suggesting a transposition in the source. Denison's grand totals agree with the deposit rows, not the subtotals; both are carried exactly as disclosed.

Inferred uranium resource on the Waterbury Lake property, estimated at a 0.10% U3O8 cut-off grade. It is the only deposit in the Waterbury inferred subtotal. 2025 activity on the property included an evaluation drilling program and a hydrogeological drilling program.

Historical uranium estimates for the Southwest and Southeast Pods at McClean South on the McClean Lake property. The estimates do not comply with NI 43-101 and CIM definitions are not used; tonnages are reported in tons rather than tonnes. In July 2025 Denison and Orano Canada announced several significant new intercepts of shallow high-grade uranium mineralisation at the McClean South zone from a 6,400-metre drilling programme completed in the first half of 2025. Denison is not treating these as current mineral resources.

Uranium project held indirectly through Denison's 50% ownership of JCU, which holds 34.4508%, giving Denison an effective 17.2254% interest; UEX is the operator. The inferred resource is supported by a technical report with an effective date of December 31, 2021 filed in March 2023 and was estimated at a 0.20% U3O8 cut-off grade.

Non-Athabasca uranium project in Nunavut held indirectly through Denison's 50% ownership of JCU, which holds 33.8118%, giving Denison an effective 16.9059% interest; Orano Canada is the operator. The estimates are as reported by Orano SA in its 2023 Activities Report and converted for grades from %U to %U3O8 and for pounds from tonnes U to pounds U3O8; cut-off grades and the assumptions, parameters and methods used are unknown. Denison is not treating these as current mineral resources.