COSA.V · 2026-04-13 12:00:00

Cosa Reports Anomalous Radioactivity in Multiple Drill Holes at the Murphy Lake North Joint Venture with Denison Mines

Mergers & Acquisitions Exploration Programs Partnerships & JV

Cosa Reports Anomalous Radioactivity in

Multiple Drill Holes at the Murphy Lake North

Joint Venture with Denison Mines

Vancouver, British Columbia--(Newsfile Corp. - April 13, 2026) -

Cosa Resources Corp. (TSXV:

COSA) (OTCQB: COSAF) (FSE: SSKU)

Cosa

" or the "

Company

") is pleased to report the

intersection of anomalous radioactivity in multiple drill holes and completion of the winter 2026 drilling

program at the Company's Murphy Lake North Project ("

MLN

" or the "

Project

"). MLN is a joint venture

(the "

Joint Venture

") between Cosa and Denison Mines Corp.

(TSX: DML) (NYSE American:

DNN)

Denison

") and is located 3 kilometres east of IsoEnergy's Hurricane deposit in the eastern

Athabasca Basin, Saskatchewan (Figure 1). Cosa is the operator and holds a 70% interest with

Denison holding a 30% interest.

Highlights

Radioactivity intersected in three drill holes

Radioactivity remains open in multiple directions including for at least 600 metres along strike to

the east and 600 metres to the west within the larger kilometre-scale Cyclone alteration zone

Depth of the radioactivity is shallow at approximately 260 metres vertically from surface

Cyclone trend structural corridor is over 100 metres wide and hosts significant alteration consistent

with major eastern Athabasca uranium deposits

Keith Bodnarchuk, President and CEO, commented:

"Intersecting radioactivity in multiple drill holes is

a tremendous result for Cosa, emphasizing the potential size and scale of this mineralizing system.

The radioactivity alone is significant, but when factoring in the open space, depth, strong alteration

and structure, this suggests we may be on the cusp of even more exciting results. With strong support

from Denison Mines, assays pending, a healthy treasury, and numerous follow up targets, 2026 is

shaping up to be a transformational year for Cosa."

Andy Carmichael, Vice President of Exploration, commented:

"Intersecting 5 metres of continuously

anomalous radioactivity in the second round of drilling at Cyclone significantly upgrades the trend.

Though warming conditions curtailed follow up, the additional holes resulted in additional radioactive

intercepts separate from that of MLN26-013 and a deeper understanding of the trend's geology which

will be invaluable during future drilling. With 600 metres of open strike length in either direction along

a mineralized structural corridor, we're eager to resume drilling in summer 2026."

MLN Winter Drilling Approach

Winter drilling at MLN followed up structure and alteration intersected at the Cyclone trend in summer

2025 (Figure 2). Five drill holes totaling 2,015 metres were completed during the program with three drill

holes intersecting anomalous radioactivity

. The first drill hole of the program, MLN26-013, intersected

the strongest radioactivity including a 5.0 metre interval of continuously anomalous radioactivity in the

upper basement (see Cosa's news release dated March 24, 2026). Two holes were completed to

directly follow up radioactivity in MLN26-013. Two additional holes were completed to define underlying

geology ahead of summer drilling and follow up another radioactive intersection. All drill holes were

completed on Section 3200E.

MLN Winter Drilling Results

Three of five drill holes intersected anomalous radioactivity (Table 1) in two discrete zones. Drilling also

defined highly prospective geology with similarities to the Hurricane deposit and other unconformity

related uranium deposits of the eastern Athabasca Basin (Figure 3).

Table 1 – Winter 2026 MLN Drilling Program Results

Hole

From

(m)

Length

(m)

Radioactivity

(CPS)

1, 2

Orientation

(Azi./Dip)

Location

MLN26-013

306.5

307.0

0.5

>350

166 / -60

Section 3200E

and

307.5

308.0

0.5

>1,000

and

308.5

313.5

5.0

>1,000

incl.

310.5

313.0

2.5

>5,000

incl.

310.5

311.0

0.5

>13,000

MLN26-014

278.5

278.6

0.1

>350

170 / -75

Section 3200E

MLN25-015

No significant radioactivity

000 / -90

Section 3200E

MLN26-016

286.5

287.5

1.0

>350

165 / -65

Section 3200E

MLN26-017

No significant radioactivity

000 / -90

Section 3200E

Radioactivity is total gamma from drill core measured with an RS-125 hand-held spectrometer

Measurements of total gamma on drill core are an indication of uranium content but may not correlate with chemical assays

Previously released

Radioactivity

Multiple intervals of anomalous radioactivity were intersected in two discrete zones (Table 1, Figure 3).

All radioactive intersections are associated with faulting and broad zones of strong hydrothermal

alteration in the sandstone and basement. All radioactive intersections remain open along strike to the

east and west for at least 600 metres and some intersections remain open on section.

MLN26-013, the first hole of the winter program, intersected a significant zone of structure and alteration

underlain by faulted graphitic gneiss hosting several intervals of anomalous radioactivity between 306.5

and 313.5 metres ranging from 400 to 13,900 cps.

Radioactivity in MLN26-013 was followed up to the north (MLN26-014) and south (MLN26-015). MLN26-

014 intersected anomalous radioactivity in the upper basement within a 0.5 metre strongly altered

interval. Elevated radioactivity was intersected in the lower sandstone by MLN26-015.

50 metres north of MLN26-013, MLN26-016 intersected a 1.0 metre interval of anomalous radioactivity

immediately below the unconformity associated with a broad zone of strong alteration and structure.

Cyclone 3200E Geology

Drilling determined the Cyclone trend is underlain by a package of graphitic and non-graphitic pelitic

gneisses and quartzite over 100 metres in width. The full width of the mineralized structural corridor is

unknown as additional prospective graphitic rocks may lie north and south of current drilling.

Graphitic basement units host faulting and alteration. Basement faulting is best developed in the

northernmost graphitic unit where MLN26-016 and -017 intersected metre- to decametre-scale fault

zones, including a 35 metre interval that is enveloped by moderate to strong alteration (Figure 6). At the

unconformity, the northern edge of this fault zone hosts radioactivity (MLN26-016) which remains open in

several directions. 100 metres to the south, MLN26-013 and -014 intersected another graphitic fault

zone which is enveloped by alteration and remains untested at the unconformity.

Significant zones of sandstone structure and alteration are present throughout, and sandstone alteration

patterns are similar to the Hurricane deposit where widespread bleached zones and distal silicified

zones envelop broad desilicified zones cored by clay alteration (Figure 3). MLN26-013, -014, and -016

all intersected decametre-scale zones of sandstone faulting and alteration overlying the northern

graphitic fault zone (Figure 3). Zones of faulting and alteration in the upper to middle sandstones of

MLN26-013 and -016 suggest additional potential north of existing drilling.

Multiple altered basement fault zones remain untested at the unconformity and down-dip.

Next Steps

The Company and its Joint Venture partner, Denison Mines, will be finalizing summer plans in the

coming weeks. The drill remains on site for rapid startup when drilling resumes this summer.

Assays for

all winter drill holes remain outstanding.

About Murphy Lake North

MLN covers a portion of the Larocque Lake trend and is located 2.7 kilometres east of the Hurricane

deposit (Figures 1 and 2). Hurricane is the world's highest-grade indicated uranium resource and was

discovered and delineated for IsoEnergy Ltd. by current members of Cosa's team. The Larocque Lake

trend also hosts the high-grade Larocque Lake Zone, Yelka Prospect, and Alligator Lake Zone. MLN

contains the along-strike extension of basement geology underlying the Hurricane deposit (the Hurricane

trend), as well as a parallel conductive trend to the south (the Cyclone trend). Cosa's winter 2026 drill

program intersected several meters of basement hosted radioactivity within a broader zone of strong

structure and alteration at the Cyclone trend. Following up these results is the primary objective for the

remainder of 2026 at MLN.

1 – Cosa considers radioactivity anomalous when it (i) exceeds 350 cps measured with a Radiation Solutions RS-125 hand held spectrometer, (ii) is

accompanied by structure and/or hydrothermal alteration consistent with Athabasca unconformity related uranium deposits, and (iii) spectrometric

assay by RS-125 indicates uranium is the dominant source.

Figure 1 – Cosa's Eastern Athabasca Uranium Projects with Joint Venture Projects