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Project

Category

Tonnes
(m)

U
₃
O
₈ grade (%)

contained
U₃O₈ 
(m lbs)

V
₂
O
₅ grade (ppm)

contained
V₂O₅ 
(m lbs)

Hurricane

Saskatchewan

Canada

Indicated

0.1

34.50 %

48.6

Inferred

0.1

2.20 %

2.7

Tony M

Utah

USA

Indicated

1.1

0.28 %

6.6

Inferred

0.4

0.27 %

2.2

Sage Plain

Utah

USA

Indicated*

0.2

0.16 %

0.8

1.3 %

6.5

Inferred*

0.0

0.13 %

0.0

0.9 %

0.2

Daneros

Utah

USA

Indicated*

0.0

0.36 %

0.1

Inferred*

0.0

0.37 %

0.1

Ben Lomond

Queensland

Australia

Indicated*

1.3

0.28 %

8.1

Inferred*

0.6

0.21 %

2.8

Dieter Lake

Quebec

Canada

Inferred*

19.3

0.06 %

24.4

Milo

Queensland

Australia

Inferred*

88.4

0.01 %

14.0

Matoush

Quebec

Canada

Indicated*

0.6

0.95 %

12.3

Inferred*

1.7

0.44 %

16.4

Coles Hill

Virginia

USA

Indicated*

108.5

0.06 %

132.9

Inferred*

32.9

0.04 %

30.4

Total M&I – 43-101

1.1

55.2

–

Total Inferred 43-101

0.4

4.9

–

Total M&I

111.8

209.5

6.5

Total Inferred

143.4

93.1

0.2

Listing Rule

Explanation

Commentary

5.12.1

The source and date of the historical estimates or foreign estimates.

Milo: Milo Mineral Resource Statement: 22 November 2012 contained in an ASX Announcement by GBM Resources Ltd (ASX:GBZ).

Ben Lomond: McKay, A. D., 1982, Ben Lomond Deposit: In Situ Uranium Resource Estimate. Confidential Report of the Australian Atomic Energy Commission Uranium Resource Evaluation Unit.

Vigar, A & Jones, D. 2005 Technical Report on the Mining Leases Covering the Ben Lomond Uranium – Molybdenum Deposit Queensland, Australia. Prepared for Maple Minerals Corporation as a NI-43-101 Report. Available at https://ww.sedarplus.ca.

Coles Hill: The Coles Hill Mineral Resources are considered to be historic in nature. The most recent Mineral Resource estimate was prepared by Lyntek, Inc. and BRS Engineering in 2013 (Kyle, John I., P. E. and Douglas Beahm, P.E., P.G., 2013; NI 43-101 Preliminary Economic Assessment Update (REVISED), Coles Hill Uranium Property, Pittsylvania County, Virginia, United States of America, and is based upon assay and geologic data collected by the former owner, Marline Oil Co, who drilled out the project between 1979 and 1981. All assays and geotechnical data used to develop the Mineral Resource estimate for the Coles Hill project was generated from that exploration program.

Tony M: IsoEnergy’s Tony M mine project has a Mineral Resource estimate that is current within the context of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Code for Mineral Reserves and Mineral Resources (CIM Code). While the CIM Code is a foreign estimate, its classification of Mineral Resources is similar in most respects to those of the JORC Code.

Daneros: The Mineral Resource estimate for the Daneros mine project of IsoEnergy is considered to be historic in nature. Historical exploration data used in IsoEnergy’s project evaluation was derived from surface rotary and core holes drilled by Utah Power & Light and White Canyon Uranium (collectively 603 drill holes), and underground long holes (583 holes) drilled by Deneson Mines and Energy Fuels. Various Mineral Resource estimates, all of which are historical in nature and not in compliance with the JORC Code in 2009 for White Canyon Uranium and Energy Fuels, Inc. in 2012 and 2018. The data used to prepare those reports was historical exploration drilling data and geologic information from prior mining operations.

Dieter Lake: The most recent historical, foreign Mineral Resource estimate done for the Dieter Lake project in Northern Quebec is documented in two reports. The first is “2005 Exploration at the Dieter Lake Property, Quebec dated November 3, 2006” by Dahrouge Geological Consulting Ltd. for Strathmore Minerals Corporation which for the first time describes the new resource estimate. This estimate, along with an update on exploration activity from 2007 to 2011, was repeated in “Technical Report on the Dieter Lake Property, Quebec, Canada” dated October 7, 2011″, prepared GeoVector Management Inc. for Fission Energy Corp (www.sedarplus.ca). Clinton Davis was an author on both reports. Michael Guo did the 2005 modelling and was a co-author on the 2006 report. Prior to the 2005 estimate, historical resource estimates had been completed in 1981, 1989, and 2004.

Davis, C. & Guo, M. (2006). 2005 Exploration at the Dieter Lake Property, Quebec; NI 43-101 Report for Strathmore Minerals Corp, 28 p., with appendices.

Davis, C.F, (2011), Fission Energy Corp, Technical Report on the Dieter Lake Property, Quebec, Canada, NI43-101 Report for Fission Energy Corp, 47 p., with appendices (www.sedarplus.ca).

Sage Plain: Mineral resources for IsoEnergy’s Sage Plain project were estimated by an independent contractor to the project’s then current owner, Energy Fuels, Inc. and reported in the “Updated Technical Report on Sage Plain Project (including the Calliham Mine)” dated March 18, 2015 and authored by Douglas C. Peters, CPG of Peters Geosciences. The Technical Report follows the format of NI 43-101, but the author did not identify any Mineral Reserve and Mineral Resource code used to classify the mineralization. Resources were estimated by employing a polygonal method. IsoEnergy considers the Sage Plain resources to be historic in nature.

Matoush: The most recent historical, foreign Mineral Resource estimate is documented in “Technical Report on the Mineral Resource Update for the Matoush Project, Central Québec, Canada, NI43-101 Report” dated February 15, 2012, prepared by David A. Ross, R. Barry Cook, Normand L. Lecuyer, and Bruce Fielder (Melis Engineering Ltd.) of Roscoe Postle Associates Inc. (“RPA”) for Strateco Resources Inc. This report is available on www.sedarplus.ca. The historical, foreign Mineral Resource estimate was further updated by RPA in December 2012, as disclosed in a press release of Strateco dated December 7, 2012, and in Strateco Resources’ Annual Information For, dated March 21, 2013 (available on www.sedarplus.ca). RPA updated the Mineral Resource estimate for the Matoush project based on drill results available as at November 22, 2012.

Hurricane: The most recent foreign Mineral Resource estimate is documented in “Technical Report on the Larocque East Project, Northern Saskatchewan, Canada” for IsoEnergy Ltd. This report was prepared by Mark B. Mathisen of SLR Consulting (Canada) Ltd. (“SLR”). Two versions, both with an effective date of July 8, 2022, are available at www.sedarplus.ca – one with a signature date of July 12, 2022, and an amended version with a signature date of August 4, 2022. It is explained in the amended report that this Technical Report conforms to NI 43-101 Standards of Disclosure for Mineral Projects and replaces the technical report filed on SEDAR on July 19, 2022, which has been revised to correct the typographical error related to the Indicated U3O8 grades in Table 14-11, which summarizes the block model sensitivity to cut-off grade. Additional typographical errors have been corrected to align the descriptions of historical drilling in Section 6 with Table 10-1. The recommended work plan has been revised.

5.12.2

Whether the historical estimates or foreign estimates use categories of mineralisation other than those defined in Appendix 5A (JORC Code) and if so, an explanation of the differences.

Milo: The Inferred resource was calculated in accordance with JORC 2004.

Ben Lomond: The Inferred resource used JORC terminology of the time (1982).   

Coles Hill: Estimates of Mineral Resources for the Coles Hill project were prepared in accordance with Canadian National Instrument 43-101 and CIM standards that were in effect at the time that the resource estimate was prepared (2013). The estimate predates the current CIM Standards and CIM Estimation of Mineral Resources & Mineral Reserves Best Practices Guidelines, which became effective in November, 2019. IsoEnergy considers the Coles Hill resources to be historical in nature. The use of “Inferred Mineral Resources” and “Indicated Mineral Resources” follow the requirements of the CIM Code. The definitions of such classifications (“Inferred Mineral Resources” and “Indicated Mineral Resources”) are similar to those classifications under the JORC Code, and there are no differences in the definitions of “Inferred Mineral Resources” and “Indicated Mineral Resources” between the two Codes.

Tony M: The “current” Mineral Resource estimate for the Tony M project was prepared in compliance with the CIM Definition Standards for Mineral Resources & Mineral Reserves (2014), CIM Uranium Leading Practice Guidelines (2024) and Canadian National Instrument 43-101. The definitions of Mineral Resource classifications for “Indicated Mineral Resources” and “Inferred Mineral Resources” under the CIM Code are similar to the JORC Code definitions of “Inferred Mineral Resources” and “Indicated Mineral Resources”.

Daneros: Mineral resources for the Daneros Mine project were estimated for former project owner Energy Fuels, Inc. by Douglas C. Peters, CPG and this estimate is contained within the “Updated Report On The Daneros Mine Project, San Juan County, Utah, U. S. A.” dated March 2, 2018. Although the resource is considered to be historic, the estimate uses resource classifications that are the same as those of the JORC Code.

Dieter Lake: The Davis and Guo (2006) report and contained Mineral Resource estimate predate the current CIM Standards (May 2014) and CIM Estimation of Mineral Resources & Mineral Reserves Best Practices Guidelines (November 2019), and for IsoEnergy the Mineral Resources are a historical estimate under National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) and a qualified person has not done sufficient work to classify the historical estimate as current Mineral Resources. It is uncertain whether the Inferred resources in the 2006 report would qualify as Inferred resources under JORC standards.

Sage Plain: Resources estimated and reported in the 2015 Technical Report on the Sage Plain Project” are historical in nature do not appear to be consistent with Mineral Resource codes in effect at the time of the report.

Matoush: The Ross et al (2012) report and contained Mineral Resource estimate, and the historical, foreign Mineral Resource update in the March 21, 2013 Strateco Resources Annual Information Form predate the current CIM Standards (May 2014) and CIM Estimation of Mineral Resources & Mineral Reserves Best Practices Guidelines (November 2019), and for IsoEnergy the Mineral Resources are a historical estimate under National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) and a Competent Person has not done sufficient work to classify the historical estimate as current Mineral Resources. It is uncertain whether the Inferred and Indicated resources in the 2012 report would qualify as Inferred resources under JORC (2012) standards.

Hurricane: The Mathison (2022) report conforms to NI 43-101 Standards of Disclosure for mineral projects. Foreign mineral resources were classified in accordance with definitions for mineral resources in the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves dated May 10, 2014. The definitions of Mineral Resource classifications for “Indicated Mineral Resources” and “Inferred Mineral Resources” under the CIM Code are similar to the JORC Code definitions of “Indicated Mineral Resources” and “Inferred Mineral Resources”.

5.12.3

The relevance and materiality of the historical estimates or foreign estimates to the entity.

Milo, Ben Lomond, Daneros, Dieter Lake, Sage Plain, Matoush, Coles Hill: The estimate is considered relevant however not material in the context of global uranium resources held.

Tony M: The Tony M project Mineral Resources are “current” under the CIM Code and are not “historic” in nature. As such they are relevant and are material to IsoEnergy.

Hurricane: The Mathisen (2022) foreign Mineral Resource estimate, is considered to be both relevant and material to IsoEnergy.

5.12.4

The reliability of historical estimates or foreign estimates, including by reference to any of the criteria in Table 1 of Appendix 5A (JORC Code) which are relevant to understanding the reliability of the historical estimates or foreign estimates.

Milo: The estimates would require some additional work to conform to JORC 2012 however the methodologies for preparing the resource estimates have not changed significantly in comparison to previous reporting.

Ben Lomond: The estimate is indicative of the mineralisation present however substantial re-drilling and assaying, down hole surveys and radiometric logging etc would be required to provide a JORC 2012 resource estimate.

Coles Hill: Although the Coles Hill resource estimate is considered to be an accurate and relevant representation of the nature of the uranium mineralization at the project, additional work, as per the recommendations in the technical report, will be required for the resources to be reclassified as “current” under the CIM Code and the CIM Uranium Leading Practice Guidelines (2024). The existing resource estimate was prepared in accordance with the then-prevailing NI 43-101 and CIM standards, although the drill hole data that forms the basis of the resource estimate had not been confirmed at the time the estimate was prepared. While this estimate predates the current CIM Standards (2014) and CIM Estimation of Mineral Resources & Mineral Reserves Best Practices Guidelines (November, 2019), the methodologies for preparing and evaluating the resource estimates have not changed significantly in comparison to those in effect at the time of the most recent estimate (2013). The historical Mineral Resources are considered to be reliable.

Tony M: The Tony M resources are relevant and reliable in the context of evaluating the project. The resources are “current” and are not historical in nature.

Daneros: Resources at the Daneros mine are not “current” and are historic in nature. However, they may be relevant to the evaluation of the project and its exploration potential in the future.       

Dieter Lake: The historical, foreign, Inferred resources presented in both the Davis and Guo (2006) and Davis (2011) reports predate the current CIM Standards (May 2014) and CIM Estimation of Mineral Resources & Mineral Reserves Best Practices Guidelines (November 2019), and for IsoEnergy the Inferred resources are a historical estimate under National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) and a Competent Person has not done sufficient work to classify the historical estimate as current Mineral Resources. Until this work is done, the reliability of the historical Dieter Lake resource estimate is uncertain.

Sage Plain: The methodology for resource estimation used for the Sage Plain project is consistent with historical work throughout the central Colorado Plateau uranium region. Polygonal estimation methodology, and the classification of resources and/or reserves derived from such studies have served small underground uranium mining adequately for decades. While local miners are familiar with the classifications and methodologies, they are not appropriate or reliable for IsoEnergy.

Matoush: The Ross et al (2012) report and contained Mineral Resource estimate, and the historical, foreign Mineral Resource update in the March 21, 2013 Strateco Resources Annual Information Form predate the current CIM Standards (May 2014) and CIM Estimation of Mineral Resources & Mineral Reserves Best Practices Guidelines (November 2019), and for IsoEnergy the Mineral Resources are a historical estimate under National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) and a Competent Person has not done sufficient work to classify the historical, foreign estimate as current Mineral Resources. Until this work is done, the reliability of the historical, foreign Mineral Resource estimate is uncertain, and it is uncertain whether the Inferred and Indicated resources in the 2012 report would qualify as Inferred and Indicated resources under JORC (2012) standards.

Hurricane: The Mathison (2022) report conforms to NI 43-101 Standards of Disclosure for mineral projects. Foreign Mineral Resources were classified in accordance with definitions for Mineral Resources in the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves dated May 10, 2014 current CIM Standards (May 2014), and IsoEnergy reports the Mineral Resources as a compliant estimate under National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).

5.12.5

To the extent known, a summary of work programs on which the historical estimates or foreign estimates are based and a summary of the key assumptions, mining and processing parameters and methods used to prepare the historical or foreign estimates.

Milo:

The most recent JORC 2004 Mineral Resource estimate was completed for the Milo Project by Kerrin Allwood F.AusIMM and published as a JORC 2004 Resource in 2012 (Allwood.K , Nov, 2012). The Nov, 2012 historical JORC 2004 Resource estimate was calculated for co-incident TREEYO & P2O5 and a copper equivalent resource comprising Au, Ag, Cu, Mo, Co & U. The Milo JORC 2004 estimate block model was generated from 34 drillholes and 9878 samples with a total core length of 11572m, all of which were competed by GBM Resources Ltd (ASX:GBZ) from 2009 to 2012.

Detailed summaries of the GBM Resources Ltd drill programs completed from 2009 to 2012 are covered in Allwood & Norris (Feb, 2012), Allwood & Norris . (August, 2012), and Allwood & Norris (Nov, 2012). The objective of diamond drill programs from 2009 to 2012 was to verify and test the Milo deposit ( 22 drillholes, 3696 samples ) (, Allwood & Norris Feb, 2012), identify anomalous intersections in the Milo deposit for follow­ up drilling Allwood & Norris . (August, 2012), 31 drillholes for 11464m of drilling and complete a further 3 drillholes to complete the Inferred resource for an initial Scoping Study Allwood & Norris ( Nov, 2012), 34 drillholes, 11572m, 3503 RC, 8069 DD. 9878m sampled at largely 1m intervals.

Ben Lomond:

In total 73,151 m of drilling was completed with 63,292 available for the quatoed estimate. ( detailed below ). All holes were radiometrically logged. The data was digitised so that computer analysis including the restitution of logs and the estimation of resources, could be carried out at various cut-off grades.

Chemical analyses of the core gave the required control for the radiometric equivalent-grade calculations, by defining the equilibrium ratio between radiometric grade and the actual grade as determined by analysis. Extensive documentation exists on the calibration of the various spectrometers used during the drilling campaigns and a different calibration factor is used for each. The actual uranium values used are therefore a combination of actual assays and down-hole spectrometer probe readings. Correlation overall is good and discrepancies minor (McKay 1982).

The parameters used in the selection of the ore intervals were a minimum true thickness of 0.5 metres and maximum included waste (true thickness) of 5 metres. Resource zones were outlined on 25m sections using groups of intersections, isolated intersections were not included. The grades from the composites were area weighted to give the average grade above a threshold of 500 ppm uranium. The area was measured on each 25m section to give the tonnage at a bulk density of 2.603

The resource categories were chosen based on the Australian JORC code guidelines of the time. The categories were:
• Indicated — extend up to 5 metres from a drill-hole up or down dip, or half the distance to the next drill-hole if less than 5 metres.
• Inferred – extend 5 to 15 metres from a drill-hole up or down dip, or half the distance to the next drill-hole if between 5 and 15 metres.                  

Drilling 1975-1981

                                                    No. of Holes         Metres
Diamond Core Surface                   98                   19,459

Underground                                   30                   2,797
Percussion  Surface                        201                 28,915
Underground                                77                    2,582
Air Trac    Surface                         230                  9,539
SUB-TOTAL:                                   636                  63,292

1982-1984:

                                                        No. of holes   Metres
Diamond core
Surface                                          21                     4,895

Percussion 
Surface                                          43                     4,964

GRAND TOTAL:                            700                   73,151

Coles Hill:

The Coles Hill uranium deposits were discovered by Marline Oil in 1979 and 1980. Marline conducted a large-scale core drilling program to test their previously identified geophysical, radiometric, and geochemical anomalies at the project site, and this work resulted in the initial definition of the Coles Hill North and South uranium deposits. The Marline core drilling program extended into 1981, and the data generated from that drilling program has served as the basis for all subsequent resource estimations. In 1982 Union Carbide Corporation (later known as Umetco) entered into a joint venture with Marline with the objective of preparing a feasibility study that would lead to the development of the Coles Hill uranium deposits and advance the project to a production status. Mineral resource estimates for the project that are considered to be relevant to the project were prepared utilizing the radiometric and chemical assays derived from the 1979-1981 drilling program of 263 core holes, as well as 3 core holes drilled at the property in 2008. The fundamental assay and geological data for the project was preserved, and a significant portion of the core was stored in covered facilities. Comparison of historical assay data with “check” assays from sampling programs in 2008 and 2013 generally confirmed the validity of the historical data. The Mineral Resource estimate for the project were estimated by BRS Engineering, a Wyoming-based independent minerals exploration and engineering company that has extensive experience in the evaluation of uranium projects. BRS employed radiometric assay data from 264 drill holes to develop the estimate of Mineral Resources at Coles Hill. Drill hole assay data was compiled in Datamine software at an interval of 0.50 feet within a “mineralized envelope” of 0.02% eU3O8 to constrain grade interpolation. A sample composite of 1.0 feet was selected.

The kriging methodology employed optimum block sizes and the optimum number of samples to access in the estimate were determined by a number of test runs on strategically placed blocks in high density and low-density areas in each area. The optimum parameters were determined by observing what produced the best regression slope (R) and kriging efficiency, and the lowest spread in 90% confidence limits, but still retaining the smallest block size relating to the probable future smallest mining unit (“SMU”). These three parameters produced good correlations amongst themselves. Three separate searches were affected, namely 1 times the range of the variogram, 1.5 times the range of the variogram and 2 times the range of the variogram. For the North Coles a minimum of 17 samples and a maximum of 25 samples were deemed to be geostatistically appropriate for the first two searches. The 3rd search was set at a minimum of 8 samples and a maximum of 25 samples. For the South Coles a minimum of 10 samples and a maximum of 20 samples for the first two searches and for the 3rd a minimum of 8 samples and a maximum of 20 samples were deemed to be appropriate (Figures 19 and 21). The search was confined to a specific layer due to the vertical variability of the mineralization and therefore the octant search method was deemed unnecessary. A draft NI 43-101 Preliminary Economic Assessment date (Revised) on the Coles Hill project was prepared for former owner Virginia Energy in 2013 by John Kyle of Lyntek, Inc. and Douglas Beahm, principal Engineer of BRS Engineering, Inc. This study, which is not publicly available, includes data verification information for all of the drill hole information, including assays, as well as summaries of metallurgical testing undertaken by Umetco Minerals, proposed mining methods, metallurgical recovery methods, and proposed project infrastructure. Copies of this report are in IsoEnergy’s files. This study of the Coles Hill project included data on mining and mineral processing methodologies in sufficient detail to identify cut-off grade criteria for estimation of Mineral Resources.

Tony M:

The Tony M uranium deposit and several other similar and nearby deposits were discovered in a remote part of southeast Utah in the mid 1970s by Plateau Resources, a subsidiary of a midwestern US electrical utility company. Plateau’s discovery was made through wide-spaced exploration drilling in an area of several very small-scale underground mines. The newly discovered deposits were outlined by conventional “open hole” rotary drilling and “spot “coring of potentially economic mineralization within favorable flat lying sandstones. Plateau commenced with the development of a large-scale room and pillar underground mine in 1978. There was limited uranium production from Tony M prior to its shut-down in 1984, but production was restarted for a short period of time in 2007-2008, before being shut down again due to low commodity prices. From the time of discovery to shut-down of mining operations at Tony M a considerable amount of drill data from surface drilling and underground long-hole drilling was collected, and that data, as well as mine operational data and metallurgical recovery information provided a substantial foundation for a new Mineral Resource estimate that was prepared in 2022 by SLR International Corporation. and these data conform to Canadian National Instrument 43-101 Standards of Disclosure for Mineral Projects. The report, entitled “Technical Report on the Tony M Mine, Utah, USA Report for NI 43-101” is dated September 9, 2022, and can be viewed via IsoEnergy’s profile on the SEDAR Plus web site (accessed 8/11/2025). The resource estimate was based upon the results of 1,678 vertical conventional (“open hole”) rotary drill holes, totalling 947,610 feet. One thousand six hundred seventy of the drill holes were completed by former owner of the Tony M mine Plateau Resources and the remainder (eight) were completed by IsoEnergy. The eight IsoEnergy holes were drilled as offsets to holes previously drilled by Plateau in order to confirm the results of the historical drill holes. The holes drilled by IsoEnergy included 2,555 feet of “conventional” open hole rotary drilling and 439 feet of core. All holes were vertical in orientation. Mineral resources at the Tony M project were classified in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves, dated May 10, 2014, definitions which are incorporated by reference in NI 43-101.

SLR estimated the resources using a conventional block modelling approach utilizing the inverse squared (ID2) methodology and length-weighted 1.0- foot uncapped composites to estimate the uranium grades (% eU3O8) in a three-pass approach. The resource estimate was based upon a US$65 per pound uranium price, and a cut-off grade oof 0.14% eU3O8. IsoEnergy is in possession of all of the technical data used to prepare the current Mineral Resource estimate.

Daneros: The Daneros mine project has been the site for numerous exploration and development activities since the early 1950s. Much of the data from those efforts has been lost or is not accessible to IsoEnergy. Recent mine production and exploration undertaken by IsoEnergy has provided data for evaluation of the project and exploration planning but is not complete enough for a new resource estimate or for updated mine planning.

Dieter Lake: Based on the Davis and Guo (2006) and Davis (2011) reports, the 2006 historical, foreign Mineral Resource estimate, which is repeated in the 2011 report, used both 2005 drill core resampling data and historic data from 96 drill holes. Resource modelling was also updated in 2005 as part of the evaluation of the data collected during the 2005 exploration program and compared to the existing historical resource model. This estimate used 200 m radius polygons, a minimum cutoff of 200 ppm over 1 metre, and a density of 2.67g/cm³.

Sage Plain: Records of exploration results and uranium production from the Sage Plain project area are generally limited to borehole gamma-ray logs, and drill hole maps of programs carried out periodically, and they have served as the basis for the historical estimates. The historic resource estimates for the Sage Plain project were generally calculated using either a polygonal or circle-tangent modelling method, both of which have been superseded by more applicable geostatistical resource estimation methods. Summaries of historical exploration and mining activities at the Sage Plain project are not available to IsoEnergy. The historical resource estimates do not conform to either the current JORC Code or the CIM Code.

Matoush: The Ross et al (2012) historical, foreign Mineral Resource estimate in the NI43-101 report dated February 15, 2012 for Strateco Resources utilized drill hole data available as of December 31, 2011 when the Matoush Gemcom database included 515 diamond core holes up to and including hole MT-11-039. Of these, 392 holes representing 175,190 m of drilling are located within the area of resources. The wireframe models representing the mineralized zones are intersected by 150 drill holes. As of December 31, 2011, chemical analyses for all holes had been received. Equivalent U3O8 (eU3O8) values were not used for this resource estimate, as was done in previous resource estimates. A set of cross-sections and plan views were used to construct three-dimensional wireframe models at a cut-off grade of 0.1% U3O8. High-grade values were cut to 9% U3O8 prior to compositing. Outlines of the mineralized lenses were interpreted on ten-metre spaced vertical sections. Minimum criteria of 0.1% U3O8 over 1.5 m true thickness was used as a guide. Narrow intercepts grading 0.05% to 0.1% U3O8 located adjacent to the main mineralized intercept were included. Where necessary, the wireframe intercept was “bulked out” to a minimum of 1.5 m true thickness. Low-grade intercepts were included in the initial wireframe models for zones MT-34 and MT-22. Many of these intercepts were removed by clipping the resource wireframe if below 0.1% U3O8. Some intersections grading 0.05% to 0.1% U3O8 were included in the grade interpolation to preserve continuity and/or maintain a soft boundary. Variogram parameters were interpreted from two-metre composited values. Sample intervals within the wireframe models range from ten centimetres to five metres, and average 70 cm. Assays within the wireframe models were composited to two-metre lengths starting at the first mineralized wireframe boundary from the collar and resetting at each new lens wireframe boundary. Several shorter composites occur at the bottom of the mineralized zone, immediately above where the drill hole exits the wireframe. Partial composites less than 60 cm long were removed from the dataset. Non-assayed intervals were treated as zero grade. Block U3O8 grades within the wireframe models were estimated by ordinary kriging. For density, RPA reviewed results of 945 bulk density measurements made by Strateco technicians using the water immersion method. RPA concluded that smaller samples may have poor accuracy and precision, and therefore elected to use only samples weighing greater than 450 g to calculate the average density of mineralization at 2.6 t/m3. This factor was then used to convert resource volumes to a tonnage. RPA manually classified the Mineral Resources based on drill hole spacing, geology, lens thickness, continuity, and variogram ranges. Most areas of Indicated are supported by 30 m to 40 m drill hole spacing, with some exceptions in areas of thicker and more continuous mineralization where drill hole spacing up to 50 m was included. The drill hole spacing in the AM-15 zone is generally less than 20 m. The MT-34 (Main lens), South lens, and most of the North Lens were classified as Indicated. Although there are some areas of closely spaced drilling in the upper MT-34 (part of AM-15 zone) and South lenses, no blocks were classified as measured because grade and geometrical continuity has not been established to the confidence level required for the measured category.

Several shorter composites occur at the bottom of the mineralized zone, immediately above where the drill hole exits the wireframe. Partial composites less than 60 cm long were removed from the dataset. Non-assayed intervals were treated as zero grade. Block U3O8 grades within the wireframe models were estimated by ordinary kriging. For density, RPA reviewed results of 945 bulk density measurements made by Strateco technicians using the water immersion method. RPA concluded that smaller samples may have poor accuracy and precision and therefore elected to use only samples weighing greater than 450 g to calculate the average density of mineralization at 2.6 t/m3. This factor was then used to convert resource volumes to a tonnage. RPA manually classified the Mineral Resources based on drill hole spacing, geology, lens thickness, continuity, and variogram ranges. Most areas of Indicated are supported by 30 m to 40 m drill hole spacing, with some exceptions in areas of thicker and more continuous mineralization where drill hole spacing up to 50 m was included. The drill hole spacing in the AM-15 zone is generally less than 20 m. The MT-34 (Main lens), South lens, and most of the North Lens were classified as Indicated. Although there are some areas of closely spaced drilling in the upper MT-34 (part of AM-15 zone) and South lenses, no blocks were classified as measured because grade and geometrical continuity has not been established to the confidence level required for the measured category.

In 2012, Strateco Resources carried out an additional 15,000-metres drilling, including some 11,000 metres of definition drilling aimed at outlining the Indicated resource within the boundaries of the new Inferred resource zones. On December 7, 2012, the Strateco Resources announced the results of the latest Matoush project historical, foreign Mineral Resource update by RPA, which showed that the Indicated Mineral Resource had increased since the previous resource estimate, dated February 15, 2012. The update was based on drill results available as of November 22, 2012 and was also published in their March 21, 2013 Annual Information Form which is available on www.sedarplus.ca

Hurricane: The cut-off date of the Mineral Resource database is March 22, 2022, which represents the date in which all assays were received from IsoEnergy’s Winter 2022 drill program. The Hurricane resource database, dated March 22, 2022, includes drill hole collar locations (including dip and azimuth), assay, alteration, geochemical, and lithology data from 106 drill holes totalling 37,875.3 m of drilling completed from 1983 through spring of 2022. A total of 785 samples of the 1,504 in the database were contained within the mineralized uranium wireframes. The wireframe models representing the Hurricane low-grade (LG), medium-grade (MG) and high-Grade (HG) mineralized zones are intersected by 48 of 106 drill holes. Geological interpretations supporting the estimate were generated by SLR and reviewed by IsoEnergy personnel. Wireframe models of mineralized zones were used to constrain the block model grade interpolation process. The models represent grade envelopes using the geological interpretation described above as guidance.

The wireframes consisted of a LG domain using a nominal COG of 0.05% U3O8 and a minimum core length of one metre. SLR considers the selection of 0.05% U3O8 to be appropriate for construction of mineralized wireframe outlines, as this value reflects the lowest COG that is expected to be applied for reporting of the Mineral Resources in an underground operating scenario and is consistent with other known deposits in the Athabasca Basin. Sample intervals with assay results less than the nominated COG were included within the mineralized wireframes if the core length was less than two metres or allowed for modelling of grade continuity. Wireframes of the MG and HG domains were created using a grade intercept limit equal to or greater than one metre with a minimum grade of 5% U3O8 and 25% U3O8, respectively, although lower grades were incorporated in places to maintain continuity and to meet a minimum thickness of one metre.

Uranium outliers were capped at 5% U3O8 and 20% U3O8 within the LG and MG domains, resulting in a total of 10 capped assay values. No capping was applied to the HG domain. SLR’s QP chose to limit the influence of the higher grade composites by employing spatial restriction in the High Grade domain. SLR used the Leapfrog restrictive search tool “clamp” that reduces the high value to a threshold value once the maximum distance is reached rather than discarding the high grade composite completely. The maximum distance of influence was set to 15 m x 15 m x 1.5 m with a grade x density threshold value of 250 (approximately equivalent to 55% U3O8) in both estimation passes. Composites were created from the capped, raw assay values using the downhole compositing function of Seequent Leapfrog Geo modelling software package. The composite lengths used during interpolation were chosen considering the predominant sampling length, the minimum mining width, style of mineralization, and continuity of grade, and ranged from 0.5 m to 3.0 m within the wireframe models, with 97.2% of the samples taken at 0.5 m intervals. Given this distribution, and considering the width of the mineralization, the SLR QP chose to composite to one metre lengths. Assays within the wireframe domains were composited starting at the first mineralized wireframe boundary from the collar and resetting at each new wireframe boundary. Assays were capped prior to compositing. A small number of unsampled and missing sample intervals were ignored. Residual composites were maintained in the dataset.

SLR generated downhole, omni-directional, and directional variograms using the one metre U3O8 composite values located within the LG and MG mineralized domains. The MG domain variogram was calculated using composites located within MG and HG wireframes to allow for more pairs in the analysis. The variograms were used to support search ellipsoid anisotropy, linear trends observed in the data, and Mineral Resource classification decisions. The downhole variograms suggests a relative nugget effect of approximately 10%. Long range directional variograms were focused in the primary plane of mineralization, which commonly strikes northeast and horizontally across the strike direction. Most ranges were interpreted to be 27 m to 35 m. The uranium grade was used to estimate the density of each sample with the polynomial formula. Densities were then interpolated into the block model to convert mineralized volumes to tonnage and were also used to weight the uranium grades interpolated into each block. All modelling work was carried out using Leapfrog Edge version 2021.2.4 software. The Hurricane block model has 5 m x 2 m x 1 m whole blocks. A regularized whole block approach was used whereby the block was assigned to the domain where its centroid was located. The variables Grade, Density, and Grade x Density were interpolated for U3O8 using the inverse distance cubed (ID3) methodology. Estimation of grades was controlled by mineralized wireframe zones. In order to reproduce the direction of the thin, folded, and faulted domains, SLR employed a variable orientation tool in Leapfrog Edge. The tool allows the search to be locally adjusted to the orientation of the mineralization, which results in improved local grade estimates. SLR used the hanging wall and footwall of each domain to guide the variable direction search.

Hard boundaries were used to limit the use of composites between different mineralization domains for U3O8 interpolation. SLR validated the block model using the following methods:

•         Swath plots of composite grades versus ID3, ordinary kriging (OK), and nearest neighbour (NN) grades in the X, Y, and Z

•         Volumetric comparison of blocks versus wireframes

•         Visual Inspection of block versus composite grades on plan, vertical, and long section

•         Statistical comparison of block grades with assay and composite grades

SLR found grade continuity to be reasonable and confirmed that the block grades were reasonably consistent with local drill hole composite grades.

A review of other uranium development projects and operating mines in the Athabasca Basin was undertaken to ascertain certain operating parameters as they relate to the estimate of a cut-off grade (COG).

The following assumptions were used in the development of the COG for Hurricane:

•         Hurricane would be developed using remote mining extraction methods similar to other development projects or operating mines in the Athabasca Basin.

•         Metallurgical recovery is assumed to be similar to other past and present uranium mines in the Athabasca Basin.

•         The long-term U3O8 price is assumed to be US$65/lb U3O8, and the exchange rate is assumed to be C$/US$ = 0.75.

•         Provincial revenue royalties are based on guidelines published by the Saskatchewan government.

•         Operating costs would be representative of a remote mining extraction method.

Applying these factors resulted in a COG of 1.00% U3O8.                                  

Classification of Mineral Resources as defined in Canadian Institute of Mining, Metallurgy and Petroleum definition Standards for Mineral Resources and Mineral Reserves (CIM 2014) were followed for classification of Mineral Resources.

The SLR QP has considered the following factors that can affect the uncertainty associated with each classification of Mineral Resources: reliability of sampling data, confidence in interpretation and modelling of geological and estimation domains, and confidence in block grade estimates. The SLR QP offers the following conclusions related to each of these factors:

•         Reliability of sampling data:

o    Drilling, sampling, sample preparation, and assay procedures follow industry standards.

o    Data verification and validation work confirm drill hole sample databases are reliable.

o    No significant biases were observed in the QA/QC analysis results.

•         Confidence in interpretation and modelling of geological and estimation domains:

o    Mineralization domains are interpreted manually in cross-sections and refined in longitudinal sections by an experienced resource geologist.

o    There is good agreement between the drill holes and mineralization wireframe shapes

o    The mineralization wireframe shapes are well defined by sample data in areas classified as Indicated.

•         Confidence in block grade estimates:

o    Indicated block grades correlate well, spatially and statistically, with composite data, both locally and globally.

Blocks were classified as Indicated or Inferred based on drill hole spacing, confidence in the geological interpretation, and apparent continuity of mineralization. All the blocks within the HG domains and blocks within the MG domain with apparent grade continuity from two or more holes were classified as Indicated. For the LG grade domain, blocks that did not meet the criteria of grade x thickness (GT) greater than or equal to 1.0%*m were removed from the Mineral Resource reporting. All remaining blocks within the MG and LG domains were assigned an Inferred category.

5.12.6

Any more recent estimates or data relevant to the reported mineralisation available to the entity.

Milo, Ben Lomond, Coles Hill, Tony M, Daneros, Dieter Lake, Sage Plain, Matoush, Hurricane: No more recent estimates have been completed or data relevant to the reported mineralisation is available.

Additional technical information, derived primarily from exploration drilling, is limited in scope and has no impact upon the Mineral Resource estimates.

5.12.7

The evaluation and/or exploration work that needs to be completed to verify the historical estimates or foreign estimates as Mineral Resources or Ore Reserves in accordance with Listing Rules Appendix 5A (JORC Code).

For all projects, it is noted that IsoEnergy is not required to disclose its Mineral Resources or Ore Reserve estimates in accordance with the JORC Code, as it is a Canadian entity and is not admitted to the official list of ASX. Accordingly, there is no present intention to undertake work for the purposes of reporting IsoEnergy’s Mineral Resource estimates in accordance with the JORC Code.

Milo: The data would require review and preparation of a Table 1. The copper equivalent would require updating in line with JORC 2012. 

Ben Lomond: A substantial re-drilling / drilling campaign would be required with the associated work necessary to report the resource in accordance with JORC (2012).

Coles Hill, Tony M: It is expected that all future Mineral Reserve and Mineral Resource estimates of IsoEnergy will be prepared in accordance with the then-prevailing Canadian Institute of Mining, Metallurgy and Petroleum Code and Canadian National Instrument NI 43- 101. Planning and scheduling of future work that may be required to advance the Mineral Resources from an historical classification to a current Mineral Resource, as defined by the CIM Code, will be done as technical evaluation of the project is progressed.

“Offset drilling” of key drill holes in the Coles Hill North and Coles Hill South uranium deposits will be required to confirm the validity of the historical drill results from the Marline Oil drilling program.

Only a limited drilling program would be required to verify the Tony M resources under the JORC Code.

Daneros: Additional work required to evaluate, confirm, and upgrade the historical Mineral Resources at Daneros would by rotary and core drilling to validate historical drilling information, and infill rotary and core drilling to test potential extensions to known mineralized zones, and underground long hole drilling.

Dieter Lake: The competent person of the independent geological consulting firm that IsoEnergy engaged in 2025 to update the Dieter Lake historical foreign resource estimate to current NI43-101 and CIM standards recommended that historic drill hole data verification will be required – including a visit to the property to verify drill hole locations and carry out verification sampling. The property visit was done in July 2025. Verification samples were collected but helicopter issues prevented conformation of drill hole collar locations from being completed. The consultant’s report is pending. There is no present intention to report the estimate in accordance with the JORC Code (2012) edition, as IsoEnergy is not presently required to comply with this reporting code.

Sage Plain: Historic resources at the Sage Plain project could be advanced to “current” status under the CIM Code through additional rotary and core drilling programs. Any future Mineral Reserve and Mineral Resource estimates of IsoEnergy Limited will be prepared in accordance with the then-prevailing Canadian Institute of Mining, Metallurgy and Petroleum Code and the context of Canadian National Instrument NI 43- 101.

Matoush: An evaluation of the work required to verify the historical, foreign mineral resource estimates as Mineral Resources or Ore Reserves in accordance with JORC 92012) code has not been done.

Hurricane: An evaluation of the work required to verify the foreign mineral resource estimates as Mineral Resources or Ore Reserves in accordance with JORC (2012) code has not been done.

5.12.8

The proposed timing of any evaluation and/or exploration work that the entity intends to undertake and a comment on how the entity intends to fund that work.

Milo: Further drilling is planned to extend the resource. The entity can fund that work from existing capital. Initial Reverse Circulation drill program of 1,000m being contemplated for Q2 2026.

Ben Lomond: Not presently planned.

Coles Hill: Drilling to confirm the historical drill results is yet to be planned but will be funded from existing sources.

Tony M: Current work at the Tony M project relates to assessment of technical topics that may have a bearing on future development and operation of the Tony M mine. Such a work program has not been scheduled. This work is being funded through IsoEnergy’s current budget.

Daneros: A confirmation drilling program at the Daneros project has not yet been scheduled. Future work at the Daneros project would be funded by IsoEnergy’s existing resources.

Deiter Lake: IsoEnergy has engaged an independent geological consulting firm to update the historical Mineral Resource estimate to current NI43-101 and CIM standards. It is anticipated their report will be received by December 31, 2025 but until their evaluation of historical drill hole data is complete it is uncertain whether the Mineral Resource estimate will be received in 2025.

Sage Plain: Exploration and confirmation drilling for the Sage Plain project has not yet been scheduled. Future activities at the Sage Plain project will be funded through IsoEnergy’s existing resources.

Matoush:  There is no present intention to report the estimate in accordance with the JORC Code (2012) edition, as IsoEnergy is not presently required to comply with this reporting code.

Hurricane:  There is no present intention to report the estimate in accordance with the JORC Code (2012) edition, as IsoEnergy is not presently required to comply with this reporting code.

5.12.9

A cautionary statement proximate to, and with equal prominence as, the reported historical estimates or foreign estimates stating that:

•       the estimates are historical estimates or foreign estimates
and are not reported in accordance with the JORC Code;

•       a competent person has not done sufficient work to classify
the historical estimates or foreign estimates as Mineral Resources or Ore Reserves in accordance with the JORC Code; and

•       it is uncertain that following evaluation and/or further exploration work that the historical estimates or foreign estimates will be able to be reported as Mineral Resources or Ore Reserves in accordance with the JORC Code.

A proximate cautionary statement has also been included within the main body of this announcement as required.

5.12.10

A statement by a named competent person or persons that the information in the market announcement provided under rules 5.12.2 to 5.12.7 is an accurate representation of the available data and studies for the material mining project. The statement must include the information referred to in rule 5.22(b) and (c).

The information in this announcement provided under ASX Listing Rules 5.12.2 to 5.12.7 is an accurate representation of the available data and studies for the IsoEnergy projects and has been reviewed by the competent person or persons named below.

Milo, Ben Lomond: Peter James Mullens. Peter James Mullens is an employee of IsoEnergy and a fellow of the Australian Institute of Mining and Metallurgy. Mr Mullens consents to the inclusion in this release of the matters based on that information in the form and context in which it appears.

Daneros, Sage Plain, Coles Hill, Tony M: Dean T. Wilton. Dean T Wilton is a consultant to IsoEnergy, a member of the Australian Institute of Professional Geoscientists and a Certified Professional Geologist as designated by the American Institute of Professional Geologists. Mr Wilton consents to the inclusion in this release of the matters based on that information in the form and context in which it appears.

Dieter Lake, Matoush, Hurricane: Daniel Brisbin. Daniel Brisbin is an employee of IsoEnergy and a member of Association of Professional Engineers and Geoscientists of Saskatchewan. Mr Brisbin consents to the inclusion in this release of the matters based on that information in the form and context in which it appears.