IsoEnergy Provides 2025 Athabasca Basin Exploration Update and Prepares to Launch Winter Exploration Programs Including Drilling at Larocque East
IsoEnergy Provides 2025 Athabasca Basin Exploration Update and Prepares to
Launch Winter Exploration Programs Including Drilling at Larocque East
Toronto, ON, December 3, 2025 – IsoEnergy Ltd. (“IsoEnergy”, or the “Company”) ( NYSE American: ISOU;
TSX: ISO) is pleased to provide an update on its summer drill programs at the Larocque East and Hawk projects
and report uranium geochemistry results received to date from the winter and summer drill programs at
Larocque East. Summer drilling at Larocque East totalled 9,561 m in 22 holes, bringing the year-to-date total
to 15,597 m in 39 drill holes (Figure 1). Drilling successfully tested both Hurricane potential resource expansion
areas and greenfield exploration targets along the prospective Larocque Trend, returning strongly anomalous
radioactivity and uranium geochemistry from multiple holes across both the winter and summer programs.
At Hawk, four drill holes were completed for a total of 3,593 m (Figure 2).
Highlights
• Resource expansion drilling returned strongly anomalous geochemistry results along the Hurricane
Main and South trends that validate previously reported radiometric results (Table1).
o LE25-194 intersected 0.872% U3O8 over 0.5 m within a 3.5 m interval, averaging 0.313% U3O8
in the basal sandstone along the Hurricane Main Trend 80 m east of the deposit.
o LE25-207 intersected 1.61% U 3O8 over 0.5 m in the basal sandstone immediately above the
unconformity along the Hurricane South Trend 240 m east of the deposit. A second 0.5 m
interval, 4.5 m below the unconformity, returned 1.71% U3O8.
• Larocque Trend – Area D geochemistry validates best uranium intersection to date outside of the
Hurricane Deposit.
o Geochemical results have confirmed that winter drill hole LE25-202, completed 2.8 km east
of the deposit in Target Area D, returned the strongest uranium intersection to date on the
Larocque East project outside the Hurricane area.
o LE25-202 intersected 1.05% U3O8 over 0.5 m about 20 m down hole from the unconformity in
a broader interval that returned 0.583% U3O8 over 1.5 m.
• Hawk Project – Key elements of prospective unconformity uranium geology continue to be
intersected in widely spaced drill holes on this early-stage exploration project.
o HK25-13 and HK25-16 intersected graphitic gneisses and faults along the previously untested
eastern conductor (Figure 2).
o HK25-14 intersected two significant intervals of structural disruption and prospective
alteration in the sandstone in the northern portion of the project where only two other holes
have been drilled.
• Upcoming winter drilling at Larocque East is expected to build on encouraging results to date –
Planning is well advanced, with 5,200 m in 13 holes anticipated. Integration of summer exploration
results with existing interpretations is underway to finalize 2026 drill targets and the winter work
program, with additional details to be provided in due course.
• Additional work is planned in 2026 to develop drill targets on highly prospective projects –
Geophysical surveys and interpretation are planned at the Evergreen, East Rim, Ranger, Trident and
Hawk projects (Figure 3).
• IsoEnergy strengthens its management team with the appointment of Ms. Misty Urbatsch as Vice
President, Strategy and Commercial , bringing extensive uranium exploration and marketing
experience from her years with Cameco and direct experience exploring for uranium in both in the
Athabasca Basin and Australia.
Dan Brisbin, Vice President Exploration, commented, “We are pleased that geochemical results received to
date have validated the 2025 Larocque East drill program radioactivity results. In particular, the intersection
in dr ill hole LE25 -202 nearly three kilometres east of Hurricane is the best uranium intersection on the
Larocque East project to date outside of the Hurricane deposit area , highlighting the prospectivity of the
Larocque Trend. Hawk is an early -stage project, and we believe that the inters ection of key geological
elements like graphitic basement rocks, faults in both the sandstone and basement, and indicative alteration
in widely spaced drill holes is encouraging. New geochemical data from the 2025 drill holes on both projects
will be key information for our exploration team to integrate with geophysical information and drill core
structural and alteration information as we develop targets for a 2026 drill program.”
Figure 1 – Map of the Larocque Trend on the Larocque East project showing the Hurricane deposit, drill
hole unconformity intercept locations, electromagnetic conductor traces, ANT seismic velocity anomalies,
and winter 2026 drill target areas. Geochemical and radiometric results for mineralized intervals in the nine
highlighted drill holes are provided in Table 1.
* See Qualified Person Statement below.
Table 1. Comparison of uranium geochemistry results for nine 2025 drill holes in which continuous split
core sampling was done on intervals in which radioactivity exceeded 350 cps over 0.5 m measured on core
with an RS-125 spectrometer.
Hurricane Resource Expansion Drilling
Mineralized intervals, defined as zones averaging ≥350 cps over a minimum length of 0.5 m o f core, were
intersected in nine drill holes from the 2025 drill program (Table 1). Continued testing of potential resource
expansion targets at Hurricane will be a focus of the planned winter 2026 drill program (Figure 1). Radioactivity
results from six mineralized holes from the winter program were previously reported (see news release dated
April 23, 2025). This news release includes radioactivity results from an additional three holes drilled during
the summer, along with the corresponding drill core uranium geochemistry results (Table 1). All radioactivity
results reported herein are averages over 0.5 m core intervals, measured with an RS-125 spectrometer unless
otherwise noted.
Results from the uranium geochemistry analysis are based on continuous split core samples collected through
radioactive zones. The Company is still awaiting a large volume of geochemical data from composite samples
taken through the sandstone and basement from the summer drill holes. The interpretation of the pathfinder
element geochemistry for the Laroque Trend will be updated once these sample results are received.
Main Trend Highlights
Significantly elevated uranium geochemistry was returned from winter drill holes LE25-194 and LE25-198, as
well as summer drill holes LE25-220A and LE25-231, which were drilled on the Hurricane Main Trend east of
the deposit. LE25-203, drilled in the winter north of LE25 -194, did not inters ect significantly elevated
radioactivity.
LE25-194, located 80 metres east of the Hurricane deposit, intersected a 3.5 m interval in the basal sandstone
immediately above the unconformity at 319.7 m in which drill core radioactivity ranged from 480 to 3,100 cps
over 0.5 m intervals. Anomalous geochemical results correlate well with the previously reported radioactivity.
The best value in a 0.5 m sample is 0.872% U 3O8, and the broader 3.5 m interval averaged 0.313% U3O8. The
spectral mineralogy of the sandstone in LE25-194 is dominated by illite, with lesser kaolinite and dickite, for
90 m up hole of the unconformity. Illite is the dominant clay mineral in alteration zones associated with most
Athabasca Basin unconformity uranium deposits , whereas dickite is the regional background clay mineral.
Kaolinite, chlorite and dravite are also significant alteration minerals in some deposits.
LE25-198, drilled 110 m east of LE25-194, intersected 0.114% U3O8 over 0.5 m in the basal sandstone 1.0 m
above the unconformity at 316.5 m . An average of 625 cps had been measured on core in the same 0.5 m
interval. The spectral mineralogy of the sandstone column is dominated by illite , with lesser kaolinite and
dickite for 115 m up hole of the unconformity.
LE25-220A intersected the unconformity 150 m east of LE25-194 at a depth of 369.0 m . The sandstone clay
mineral spectroscopy is dominated by strong illite, with lesser kaolinite, and an almost complete absence of
background dickite for 100 m up hole from the unconformity. Immediately below the unconformity, a 0.5 m
interval returned 0.295% U3O8, which correlates with an average of 750 cps, within a zone of strong, pervasive
clay alteration.
LE25-231 intersected the unconformity 15 m north of LE25 -220A. It intersected an average o f 313 cps
measured on the core over a 1.0 m interval 1.0 m below the unconformity at 326.0 m , within a strongly
bleached and clay-altered semipelitic gneiss. Geochemistry results are pending.
South Trend Highlights
Intervals of significantly elevated uranium geochemistry returned from winter drill holes LE25-207 and LE25-
210 on the Hurricane South Trend correlate with radioactive intervals measured on drill core.
LE25-207 was drilled 240 m east of the deposit and intersected the unconformity at 323.8 m. It returned 1.61%
U3O8 over a 0.5 m interval in the basal sandstone immediately above the unconformity where drill core
radioactivity averaged 4,600 cps over the same interval. Additionally, a second 0.5 m interval 4.5 m below the
unconformity, returned 1.71% U3O8 where drill core radioactivity averaged 8,800 cps.
LE25-210 was drilled 480 m east of Hurricane and intersected the unconformity at 320.6 m. It returned 0.486%
U3O8 over a 0.5 m interval, located three metres below the unconformity , where drill core radioactivity
averaged 3,700 cps over the same interval . This interval is within a 2.5 m interval that extends from 1.5 m
above the unconformity to 1.0 m below the unconformity that returned an average of 0.115% U3O8.
An additional ten holes (LE25-195, 197, 199, 200, 201, 208, 211, 212A, 214 and 216) drilled on the South Trend
in 2025 intersected prospective alteration and structure. The highest radioactivity measured on drill core was
650 cps over 0.1 m associated with limonitic clay-chlorite alteration immediately below the unconformity at
331.0 m in LE25- 216. In LE25- 197, 360 cps was recorded over 0.5 m in the sandstone 1.5 m above the
unconformity at 332.5 m. That interval is within a 1.0 m interval from 330.0 m to 331.0 m that returned 0.056%
U3O8.
The prospectivity of the Southern Trend remains strong, particularly given that it remains open to the east of
LE25-212A. This is supported by mineralization intersected near the unconformity in drill holes LE25 -207,
LE25-210, LE21-101 and LE22-115A. In addition, clay mineralogy within the sandstone column of the twelve
holes drilled in 2025 is dominated by illite, with lesser amounts of kaolinite and chlorite, which is an
assemblage consistent with prospective hydrothermal alterati on associated with unconformity -related
uranium systems. The prospective clay mineralogy extends for 190 m or more up hole from the unconformity
in most drill holes. Background dickite i s only a component of the lower sandstone spectral mineralogy in
LE25-210 and LE25-212.
North Trend Highlights
Drill holes LE25-196 and LE25-205A were drilled in the winter and LE25 -218 in the summer to test north of
the Hurricane deposit within the prospective ANT seismic velocity low footprint where anomalous uranium
geochemistry in historic holes indicates potential for a mineralized trend north of the deposit. Spectral
mineralogy res ults indi cate that a ll three holes inter sected prospective illite-chlorite-kaolinite-dickite
assemblages over distances between 105 and 130 m up hole of the unconformity intersections in each hole.
LE25-218 was drilled to test the unconformity down-dip of anomalous uranium geochemistry and alteration
mineralogy intersected in the sandstone column in 2020 drill hole LE20-56. The lower sandstone interval 190
m up hole from the unconformity at 353.1 m in LE20- 56 is characterized by spectral clay mineralogy
dominated by prospective illite, with lesser kaolinite and dickite, and by > 1 part per million uranium partial
values (“ppm U-p”).
LE25-218 intersected 1,300 cps over a 0.5 m interval on core 7 m below the unconformity at 368.6 m. The
same interval returned 0.312% U3O8 over 0.5 m. The elevated uranium corresponds with hematite alteration
that is flanked by patchy clay and chlorite alteration in a graphitic cordierite pelite. This graphitic basement
unit is interpreted to be about 30 m north of the graphitic host rocks and faults that underlie the Hurricane
deposit.
LE25-205A, which intersected the unconformity approximately 100 m east-southeast of LE25-218, intersected
two 0.1 m intervals at 350 cps over in the first 2 m below the unconformity at 324.5 m.
Larocque Trend Drilling
Target Area D
Winter drill hole LE25-202 intersected radioactivity with an average RS-125 reading on core of 6,200 cps over
0.5 m on the west end of Target Area D , located 2.8 km from Hurricane . This was t he highest radioactivity
intersected on the project to date outside of the immediate Hurricane area. G eochemical data for the same
interval confirm this result. The same interval returned 1.05% U3O8 over 0.5 m approximately 20 m down hole
from the unconformity at 270.3 m in a broader interval that returned 0.583% U3O8 over 1.5 m.
LE25-204 and LE25 -206 were drilled on section down -dip and up -dip, respectively, of the LE25 -202
intersection. Although both drill holes intersected prospective alteration and structure, neither intersected
significant radioactivity. To further evaluate the LE25-202 intersection, five drill holes were completed along
strike in the summer. Hole LE25-215 was drilled on strike to the northeast; and LE25-222, 225/225c1, 227 and
232 were drilled southwest of LE25- 202. The highest radioactivity encountered was 30 0 cps over 0.1 m in
graphitic pelite 6 m below the unconformity at 257.5 m in LE25-232.
Also in Target Area D, drill hole LE25 -209 was completed in the winter, and drill holes LE25-213, 217, 219A,
226A, and 229B were completed in the summer , all on a parallel trend to the southeast of LE25-202. The
highest radioactivity was 260 cps over 0.5 m at the unconformity at 275.5 m in LE25-213. This hole was drilled
195 m east-northeast of LE22-116 which intersected 369 ppm U -p over 0.5 m in basal sandstone and 2,750
ppm U-p over 0.5 m immediately below the unconformity in the basement.
Additional testing of this target area is being planned for the 2026 winter drill program (Figure 1).
Additional Target Areas E, F and K
Exploration at Target Areas E, F, and K focused on advancing several untested or lightly explored conductive
and structural features east and northeast of the Hurricane deposit.
At Target E, two summer drill holes provided initial tests of a one-by-two-kilometre ANT anomaly interpreted
to reflect folded graphitic -pyritic gneisses disrupted by northeast -trending faults. LE25-223, drilled in the
north end of Target Area E, did not encounter significant radioactivity. LE25 -224 was completed in the
southeast end of Target Area E to follow up on LE24 -192, drilled in 2024, which intersected 2.0 m averaging
495 ppm U -p straddling the unconformity. LE25 -224 intersected 400 cps over 1.0 m i n the basal sandstone
immediately above the unconformity at 226.5 m. This same 1.0 m interval returned 0.35% U3O8.
At Target F, one summer reconnaissance hole, LE25-221, evaluated coincident conductor, resistivity, and ANT
anomalies within a structurally complex corridor. Clay mineralogy in the sandstone 2 5 m up hole of the
unconformity at 263.1 m is characterized by a prospective mix of illite, kaolinite and chlorite.
At Target K, a newly defined 2.5 km conductive trend located 800 m north of the main Hurricane conductor
trend was tested through electromagnetic surveying and two reconnaissance summer drill holes, LE25-228
and LE25-230. Although the source of the conductivity was not intersected, the data collected will support
ongoing refinements to the geophysical model and future targeting in this emerging area.
Hawk Project
The Hawk Project encompasses more than 15 k m of prospective conductive strike, with depths to the
unconformity interpreted between 600 and 750 m. Summer exploration activities, designed to build on 2023
and 2024 programs, included four drill holes totaling 3,593 m, ambient noise tomography (ANT) surveys in the
northern portion to extend 2023 coverage, and stepwise moving loop (SWML) electromagnetic surveys in the
south to refine conductor interpretations based on previous fixed loop (FL) data (Figure 2).
HK25-13 and H25-16 were the first tests of the eastern conductor. They intersected the unconformity 674.5
m and 688 m down hole, respectively. Encouragingly, both intersected graphitic gneiss units in the basement,
and brittle faults and structural disruption in both the sandstone and basement. Though preliminary
interpretation of spectral mineralogy results indicates that dickite dominates the sandstone colum n clay
mineralogy, prospective alteration is present in the b asal sandstone of both holes – chlorite in HK25-13 and
mixed illite-chlorite in HK25-16.
HK25-14 was drilled to test a conductor in the northern portion of the project, where only two previous holes
have been drilled. HK25-14 intersected the unconformity at 726.5 m downhole. A conductive source was not
intersected in the basement . However, two significant intervals of structural disruption and prospective
bleached and desilicified sandstone were intersected in the middle and basal sandstone . The structural
disruption observed in the sandstone suggests that the drill hole overshot the targeted conductive basement
structure. Prospective spectral mineralogy mixtures of illite, chlorite, kaolinite and dickite are associated with
both these structurally disrupted, bleached, and desilicified intervals.
HK25-15 was drilled to test a strong conductor plate interpreted from the 2025 SWML EM survey. It
intersected the unconformity 727.8 m down hole. The conductive source was not intersected . Although
preliminary mineral spectroscopy data indicate that dickite, with lesser kaolinite, dominates the sandstone
column, three 10 m long chloritic intervals were intersected in the middle sandstone, and the basal sandstone
is characterized by a mix of illite-chlorite-dickite.
Once geochemical results have been received, the interpretation for this sparsely drilled prospective project
will be updated utilizing drill hole geology, spectral mineralogy and chemistry along with available geophysical
survey information. Additional ground electromagnetic surveys to refine drill target s will be evaluated in
conjunction with the updated project interpretation.
Figure 2 – Compilation map of Hawk project showing labeled 2025 drill hole locations, unlabeled previous
drill hole locations (both at the unconformity), and interpreted ground electromagnetic survey conductors,
on a plan view of the 20xx ZTEM conductivity model 50 metres below the unconformity.
Additional Athabasca Basin Exploration
Winter g eophysical surveys and interpretation are being planned for four projects to further develop a
pipeline of drill-ready targets on the Company’s projects in the Eastern Athabasca Basin (Figure 3). These
surveys will add to airborne, and selective ground , conductivity, magnetic, radiometric and gravity data
acquired on the Evergreen, East Rim, Ranger, and Trident projects since 2022 to evaluate unconformity and
basement-hosted deposit potential along multiple prospective corridors under shallow cover near the basin
margin.
Figure 3 – Location of IsoEnergy’s exploration projects in the eastern Athabasca Basin, highlighting
projects on which work is planned in 2026.
* See Qualified Person Statement below.
Corporate Update
IsoEnergy is pleased to announce the appointment of Misty Urbatsch as Vice President, Strategy and
Commercial. Ms. Urbatsch brings over fifteen years of diverse experience in the mining sector, combining a
strong technical foundation in uranium exploration with commercial expertise in global uranium marketing
and trading. Her career spans both field and corporate roles, providing her with a comprehensive
understanding of the metals industry from discovery through to sales.
Ms. Urbatsch began her career with Cameco Australia Pty Ltd., where she explored for unconformity -type
uranium deposits in the East Alligator River Uranium Field in the Northern Territory. She also managed
exploration programs focused on sandstone -hosted uranium syste ms in South Australia’s Frome Basin. In
2012, she relocated to Canada to join Cameco’s Saskatchewan-based exploration team, leading projects near
some of the highest-grade uranium deposits in the Athabasca Basin.