Onyx Gold Discovers New Gold Zone 250 meters from Argus North Argus West Drilling Intersects Multiple Gold Occurrences Returning 21.2 m of 2.1 g/t Au, Including 14.0 m of 3.0 g/ t Au and a Second Interval of 5.0 m of 5.1 g/t Au
December 3rd, 2025 NR# 044-2025
NEWS RELEASE
Onyx Gold Discovers New Gold Zone 250 meters from Argus North
Argus West Drilling Intersects Multiple Gold Occurrences Returning 21.2 m of 2.1
g/t Au, Including 14.0 m of 3.0 g/ t Au and a Second Interval of 5.0 m of 5.1 g/t Au
Starting 9.8 m From Surface
Demonstrates Potential for Repeated Argus North-style Mineralized Zones
Vancouver, BC – December 3rd, 2025 – Onyx Gold Corp. (“Onyx” or the "Company") (TSX-V:
ONYX, OTCQX: ONXGF) is pleased to the announce the discovery of a new zone of near-surface
gold mineralization, 250 meters (“ m”) southwest of the Argus North Zone (“Argus North”). This
new discovery the latest advancement of the Company’s ongoing 75,000 m phase I/II/III diamond
drill program (the “ Program”) at its 100% -owned Munro-Croesus Project (“Munro-Croesus” or
the “Project”), located 75 km east of Timmins, Ontario.
Results reported today from Argus West include two step-out drill holes, MC25-213 and MC25-
199, completed 250 m and 430 m respectively from Argus North along the newly prioritized Argus
Fault. This northeast–southwest-trending, moderately to steeply northwest -dipping structure is
emerging as an important control on gold mineralization. Two additional drill holes are also
reported today, which tested targets up to 925 m southwest of Argus North.
At Argus West, drill hole MC25-213 intersected multiple occurrences of visible gold (Plate 1)
returning 21.2 m grading 2. 1 grams per tonne gold (“g/t Au”) starting at 9.8 m from surface
within mafic variolitic volcanic rocks in the structural hanging wall to the Argus Fault . Drill hole
MC25-199, a further 180 m to the southwest, intersected 14.0 m grading 1.0 g/t Au hosted by
fine-grained metasedimentary rocks, in the structural footwall to the Argus Fault.
New Highlights from Argus West
• 21.2 m grading 2.1 g/t Au, in drill hole MC25-213 (250m from Argus North), including
o 14.0 m grading 3.0 g/t Au, including
1.0 m grading 19.7 g/t Au (with visible gold), AND
26.2 m grading 1.2 g/t Au, also in drill hole MC25-213, including
o 5.0 m grading 5.1 g/t Au, including
1.5 m grading 13.7 g/t Au (with visible gold)
• 38.0 m grading 0.5 g/t Au, in drill hole MC25-199 (430m from Argus North), including
o 14.0 m grading 1.0 g/t Au, including
3.0 m grading 2.4 g/t Au
• Ongoing step-out drilling at the Argus North, Main and West discoveries has now defined
broad zones of gold mineralization over a total strike length of 900 m and from surface
to ~400 m vertically.
• All of the Argus Zones remain open along strike, down-dip, and down-plunge.
• The Company has completed 85 drill holes to date, totalling >29,000 m as part of its
75,000 m Phase I/II/III drill program. Assays have been announced for 41 holes.
“Argus West is a significant new discovery that continues to demonstrate the scale potential of
the Argus gold system,” said Brock Colterjohn, President & CEO. “Intersecting near-surface gold
mineralization 250 meters southwest of Argus North in both volcanic and sedimentary host rocks
is a new and encouraging development for us, and highlights the fertility of the newly prioritized
Argus Fault. Seeing the system develop across multiple lithologies supports our view that Argus
is part of a larger, structurally controlled corridor with meaningful expansion potential. With three
rigs active, we are continuing systematic step- outs along strike and do wn-dip to continue to
evaluate the size of this new zone and the broader Argus trend.”
Discussion of 2025 Drill Results
The Argus North Zone is located on the western half of the Munro-Croesus Project, approximately
150 meters north of the regional Pipestone Fault, a major structural corridor that hosts several
significant gold deposits in the Timmins camp. The discovery hole at Argus North, MC24-163, was
reported earlier this year, and returned 69.6 m grading 3.4 g/t Au, including 34.5 m grading 5.4
g/t Au and 9.5 m grading 13.9 g/t Au (see Company news release dated April 10, 2025).
Argus North lies roughly 100 meters north of the east -west trending Argus Main Zone (“ Argus
Main”), which represents a separate 750 m x 200 m near-surface bulk-tonnage gold target (e.g.,
1.0 g/t Au over 63.3 m and 0.5 g/t Au over 136 m).
Gold mineralization at Argus North is distinguished by both broad zones (50 m to over 100 m) of
+1 g/t Au mineralization containing multiple continuous higher-grade sub-intervals (e.g. 34.5 m
grading 5.4 g/t in hole MC25-163, 24.9 m grading 5.2 g/t in MC25-232, and 5.2 m grading 5.1 g/t
in hole MC25- 180) (Figure 1). Geologically, the high- grade sub- intervals at Argus North are
closely associated with zones of strong albitization and silicification, pyritic stringers, and localized
porphyritic intrusions within variolitic basalt and volcanic breccias cut by dominant northeast -
trending faults and associated fractures. This combination of alteration and structural preparation
is interpreted to be a key control on gold deposition. Drilling to date has demonstrated excellent
vertical continuity of mineralization, now traced from surface to approximately 400 meters depth,
with the system remaining open along strike, down-dip and down-plunge.
Results reported today from the new Argus West Zone include two (2) step- out diamond drill
holes, MC25-213 and MC25- 199, which were completed 250 m and 430 m , respectively, from
Argus North Zone along the Argus Fault, a key northeast -southwest-trending, moderately to
steeply dipping structure that appears to play an important role in the locus of gold mineralization.
Drill hole MC25 -213 returned 21.2 m grading 2.1 g/t Au starting at 9.8 m from surface within
mafic variolitic volcanic rocks in the hanging wall to the Argus Fault. The variolitics are strongly
albite-altered with a moderate crackle brecciation, and fine-grained disseminated to fracture-
controlled pyrite, similar to Argus North. Multiple visible gold occurrences at approximately 27.0
m and 65.5 m depth downhole are associated with quartz ± carbonate veins that define the crackle
breccia (Plate 1). Although interpreted to be broadly equivalent mineralizing systems, the limited
observation of visible gold at Argus North indicates that Argus West may represent a distinct
mineralization style with more efficient gold deposition focused in breccia units near the Argus
Fault.
Drill hole MC25-199, a further 180 m to the southwest, intersected 14.0 m grading 1.0 g/t Au
within fine-grained metasedimentary rocks, in the foot wall to the Argus Fault. Strong sericite
alteration with an increase in quartz-carbonate veining characterizes the mineralized interval.
Drill hole MC25-215 was designed to test for gold mineralization associated with felsic intrusions
adjacent to the Pipestone Fault, located 925 m southwest of Argus North. The hole returned 1.5
m grading 4. 8 g/t A u in fine- grained metasedimentary rocks , confirming a new, fertile gold
mineralizing environment. The metasedimentary rocks are intruded by multiple quartz -feldspar
porphyritic intrusions, up to 50 m thick and are strongly sericite-altered with quartz-carbonate
veining.
Drill hole MC25-217 was collared 100 m west of drill hole MC25-199, but north of the Argus Fault
and returned no significant values.
The Company is aggressively following up on this discovery at Argus West with 50 m spaced
step-out drill holes, immediately east, west and down-dip of drill hole MC25-213, with other holes
planned to systematically test the Argus Fault along strike.
Details for drill hole assay s reported in this news release are shown in Figures 1, 2, 3, 4 and
Table 1.
Table 1 – Significant Assay Results from Recent Drilling Completed at the Argus North
Zone
Target From To Length Au
Drill Hole (m) (m) (m) (g/t)
Argus West
MC25-199 21.5 28.5 7.0 0.2
And 55.5 93.5 38.0 0.5
Including 67.5 81.5 14.0 1.0
Including 78.5 81.5 3.0 2.4
And 195.9 197.4 1.5 3.0
And 302.5 308.0 5.5 0.2
MC25-213 13.8 35.0 21.2 2.1
Including 21.0 35.0 14.0 3.0
Including 27.0 28.0 1.0 19.7
And 55.8 82.0 26.2 1.2
Including 64.8 69.8 5.0 5.1
Including 64.8 67.4 2.6 9.1
Including 64.8 66.3 1.5 13.7
MC25-215 303.5 305.0 1.5 4.8
MC25-217 No Significant Assays
*Intersections are reported as drilled width; true width is estimated to be 70- 90% of drilled width.
Figure 1 – Plan Map Highlighting Argus North/Argus West Zone Drill Holes Reported in
this Release
Figure 2 – Longitudinal Section Highlighting Argus North/Argus West Zone Drill Holes
Reported in this Release
Figure 3 – Cross Section Highlighting Argus West Zone Drill Hole MC25-213 Reported in
this Release
Figure 4 – Location of the Munro-Croesus Gold Project, Ontario