IsoEnergy Assays Find 15.4% Uranium Oxide 500 Meters Beyond the Hurricane Resource

• Assays confirm uranium mineralization in 18 of 26 summer holes across 550 meters (m) of strike on the Hurricane South Trend.
• A step-out hole 500 m east of Hurricane returned 4.17% uranium oxide over 2.0 m, including 15.4% over 0.5 m.
• A western L fault hole returned 3.86% uranium oxide over 3.5 m, including 13.8% over 0.5 m.
• Inside the deposit's southern portion, a hole returned 3.53% uranium oxide over 3.0 m in an area previously interpreted as low-grade.
• The 2026 drilling will feed an updated Hurricane geological interpretation that underpins 2027 drill targets.

Company Overview

IsoEnergy (NYSE American: ISOU | TSX: ISO) is a globally diversified uranium company with current and historical mineral resources in Canada, the US, and Australia at varying stages of development. It is advancing the Larocque East project in the eastern Athabasca Basin, home to the Hurricane deposit. Hurricane hosts a current mineral resource of 48.6 million pounds (lb) of uranium oxide at 34.5% uranium oxide indicated, and 2.7 million lb at 2.2% inferred. The deposit lies approximately 40 kilometers northwest of the McClean Lake mill, with mineralization at approximately 325 meters (m) depth.

Assays Back the Summer Radiometric Readings

Uranium assays received to date from IsoEnergy's completed 2026 summer drill program at Larocque East confirm high-grade uranium mineralization in multiple holes along the Hurricane South Trend. The mineralization sits both within the deposit's southern footprint and along-strike to the east, including approximately 500 m beyond the deposit. Assays confirm mineralization in 18 of 26 summer holes across 550 m of strike. 

The assays also confirm radioactivity results first released on September 8, 2026, which were measured on drill core with a handheld spectrometer. Those readings indicate uranium content but may not correlate with chemical assays. For all 18 holes, the radioactive intervals correspond to elevated uranium values in the assays.

Vice President, Geology of IsoEnergy, Dan Brisbin, ties the laboratory results back to the earlier field readings:

"We are pleased that uranium assay results received to date for exploration holes completed on the Hurricane South Trend in the summer have substantiated previously released radiometric results." 

The summer program completed 26 holes to target and abandoned 3 holes in sandstone, for a total of 10,159 m. Apart from 1 hole on the Hurricane Main Trend, all the drilling targeted the South Trend, made up of the J, K, and L faults. 

Step-Out Holes Return High Grades East of Hurricane

Drilling intersected mineralization beyond the existing deposit footprint on both the L and K fault zones. The highest single grade came 500 m east of Hurricane on the L fault zone, where a hole returned 4.17% uranium oxide over 2.0 m from 331.5 m downhole, including 15.4% over 0.5 m. That 15.4% sample comes from the interval with the strongest radioactivity and visible pitchblende, a uranium oxide mineral. The hole lies 29 m west along-strike of a winter hole that returned 1.00% over 1.5 m. 

On the western part of the L fault, a hole returned 3.86% uranium oxide over 3.5 m from 341.0 m, including 5.24% over 2.5 m and 13.8% over 0.5 m. It intersected the unconformity, the boundary between the basal sandstone and the older basement rock below, 50 m east of the existing footprint. The hole lies 75 m east of a winter hole that returned 4.21% over 3.5 m.

On the K fault zone, 45 m east of the deposit, a hole returned 1.03% uranium oxide over 2.0 m from 331.5 m, including 1.88% over 0.5 m. That interval is part of a broader 0.56% over 4.5 m from 330.0 m.

Higher Grades Inside the Low-Grade Shell 

One summer hole tested the L fault within the southern portion of the deposit, an area previously interpreted as part of the low-grade shell. It returned 3.53% uranium oxide over 3.0 m from 328.0 m, including 5.02% over 2.0 m and 10.8% over 0.5 m. The intercept lies in graphitic pelite, a carbon-rich metamorphic rock, below the unconformity, 11 m west of the winter hole that returned 4.21% over 3.5 m, including 11.6% over 1.0 m.

Holes drilled to test continuity along the L fault between the 2 high-grade western intercepts returned lower grades, with a best result of 0.319% uranium oxide over 0.5 m.

A 140-Meter Trend on the Central L Fault 

On the central L fault, 6 holes from west to east now define a 140 m long trend over which each hole intersected greater than 1.0% uranium oxide over at least 0.5 m. Two of them were summer holes. One returned 0.246% over 4.5 m from 326.5 m, with a best sample of 1.36% over 0.5 m, and the other returned 0.91% over 1.0 m from 322.5 m, including 1.06% over 0.5 m. 

Results on the J & K Faults & the Main Trend

Of the 6 holes that targeted the J and K faults at the unconformity, 2 intersected mineralization. Besides the K fault intercept east of the deposit, a hole on the J fault returned 0.319% uranium oxide over 3.0 m from 331.0 m, including 0.805% over 0.5 m. That hole reached the unconformity 6 m north of the optimal target. Several of the other holes are interpreted to have reached the unconformity north of the target faults or between them.

A single hole on the Hurricane Main Trend, 40 m east of the existing footprint, returned 0.056% uranium oxide over 0.5 m from 327.0 m. That one test does not close off the potential extension of Main Trend mineralization east of the deposit.

Next Steps

Geoscience information from the 43 holes completed in 2026 is being integrated with existing information as IsoEnergy updates the Hurricane area geological interpretation to underpin 2027 drill targets. Multi-element geochemical results are pending and will be added when received.

The project team is currently proposing 2027 drilling on the sparsely tested eastward projection of the L fault zone, where the 15.4% sample was returned near the east end of its drill-defined extent. A hole testing that projected extension farther east cut a fault zone at the center of an 80 m interval of strongly bleached and altered sandstone, and potential along the extension remains open.

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