Osisko Gold Confirms Presence of Mineralized System with Open Pit Potential at the Proserpine Target on the Cariboo Gold Project's Regional Property; Exploration Drilling Highlights Include 95.93 g/t Au over 4.60 m at 71 m Vertical Depth and 5.46
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NEWS RELEASE
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Osisko Gold Confirms Presence of Mineralized System with Open
Pit Potential at the Proserpine Target on the Cariboo Gold
Project's Regional Property; Exploration Drilling Highlights
Include 95.93 g/t Au over 4.60 m at 71 m Vertical Depth and 5.46
g/t Au over 8.60 m at 77 m Vertical Depth
HIGHLIGHTS
• 6,463 m in 14 drill holes of new surface exploration drilling at the Proserpine regional exploration
target, located 7 km along strike to the southeast of the Cariboo Gold deposit
• Results confirm the presence of a n emerging gold mineralized system comprising high-grade
structures exhibiting similarities to those at the Cariboo Gold deposit that, together with broader
zones of lower-grade mineralization, may indicate potential for open pit mining methods
• Highlight intercepts include: 95.93 g/t Au over 4.60 m at 71 m vertical depth (including 873.00
g/t Au over 0.50 m), 5.46 g/t Au over 8.60 m at 77 m vertical depth, and 2.17 g/t Au over 14.45
m at 431 m vertical depth
• Drilling of an additional 26,500 m planned met res, initially with three rigs , is now resuming
following a seasonal hiatus
Toronto, Ontario, August 5, 2026 – Osisko Gold Group Inc. (NYSE: OGG, TSXV: OGG) (" Osisko Gold" or the
"Company") is pleased to announce its first set of new diamond drilling results consisting of fourteen holes from
the surface exploration program on the Proserpine regional greenfield target, located within the broader Cariboo
Gold Project property boundary and approximately 7 kilometres ("km") from the Company's permitted, 100% -
owned Cariboo Gold Project (the "Project") in central British Columbia, Canada.
Chris Lodder, President, stated, “We are encouraged by the initial results from the drill campaign at Proserpine ,
which highlight the potential for a significant new gold mineralized system of scale located only 7 km from the Cariboo
Gold deposit. Drilling has intersected high-grade structures showing similarities to those at Cariboo , but also
containing areas with broader lower grade mineralization that may indicate potential for bulk mining methods. To
date, drilling has broadly tested an area measuring approximately 1.0 km x 0.5 km within a larger target of 6.0 km x
1.0 km gold-in-soil and rock anomaly. For context, the currently defined Cariboo Gold deposit extends approximately
4.0 km along strike by 0.5 km in width, underscoring the exploration potential that remains to be tested at Proserpine."
DRILL ASSAY HIGHLIGHTS
This news release contains assays from fourteen (14) diamond drillholes ("DD") totalling 6,463 meters ("m") with
depths ranging from 36.0 to 734.3 m (see Table 1 and Figure 3) completed between February and May of 2026. All
holes were collared in HQ (63.5 millimetre diameter) and reduced to NQ (47.6 millimetre diameter) where necessary
to continue advancing. Estimated true widths of intercepts are provided in Table 1. Select highlights include:
• 95.93 grams per tonne ("g/t") gold ("Au") over 4.60 m at 71 m vertical depth in PSP -26-004,
including:
– 873.00 g/t Au over 0.50 m, and
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– 3.77 g/t Au over 1.20 m
• 5.46 g/t Au over 8.60 m at 77 m vertical depth in PSP-26-001 (Figure 1), including:
– 16.05 g/t Au over 1.10 m, and
– 12.50 g/t Au over 0.87 m, and
– 10.25 g/t Au over 0.50 m, and
– 5.97 g/t Au over 0.70 m, and
– 5.21 g/t Au over 0.80 m, and
– 3.36 g/t Au over 0.60 m, and
– 1.50 g/t Au over 0.90 m, and
– 1.18 g/t Au over 0.90 m
• 2.17 g/t Au over 14.45 m at 431 m vertical depth in PSP-26-001, including:
– 35.10 g/t Au over 0.65 m, and
– 8.61 g/t Au over 0.50 m, and
– 2.21 g/t Au over 0.50 m, and
– 1.21 g/t Au over 0.50 m
• 1.46 g/t Au over 12.40 m at 295 m vertical depth in PSP-26-003, including:
– 15.40 g/t Au over 1.00 m, and
– 2.02 g/t Au over 0.50 m
• 3.17 g/t Au over 5.45 m at 334 m vertical depth in PSP-26-009, including:
– 19.30 g/t Au over 0.60 m, and
– 9.52 g/t Au over 0.50 m, and
– 1.22 g/t Au over 0.50 m
• 1.30 g/t Au over 12.00 m at 27 m vertical depth in PSP-26-011, including:
– 9.92 g/t Au over 0.70 m, and
– 6.19 g/t Au over 0.50 m, and
– 3.63 g/t Au over 0.50 m, and
– 3.75 g/t Au over 0.50 m, and
– 1.50 g/t Au over 0.65 m
• 2.93 g/t Au over 5.15 m at 233 m vertical depth in PSP-26-001, including:
– 15.60 g/t Au over 0.95 m
• 4.30 g/t Au over 3.10 m at 226 m vertical depth in PSP-26-001, including:
– 18.75 g/t Au over 0.50 m, and
– 7.54 g/t Au over 0.50 m
• 2.79 g/t Au over 4.00 m at 184 m vertical depth in PSP-26-014, including:
– 11.55 g/t Au over 0.90 m
• 2.30 g/t Au over 4.50 m at 17 m vertical depth in PSP-26-007, including:
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– 12.25 g/t Au over 0.50 m, and
– 5.62 g/t Au over 0.50 m, and
– 1.73 g/t Au over 0.50 m, and
– 1.09 g/t Au over 0.50 m
Results to date have expanded the footprint of known mineralization at Pros erpine to approximately 1.0 km along
strike by 0.5 km in width , with mineralization remaining open in all directions. All drill holes that reached their
intended target depths encountered mineralization, providing a compelling basis for systematic follow-up drilling.
Mineralization was encountered from near surface to vertical depths exceeding 400 metres. In particular, hole PSP-
26-001 returned several notable mineralized intercepts beginning at a vertical depth of approximately 55 metres
and with the deepest at more than 400 metres from surface.
FIGURE 1: 5.46 g/t Au over 8.6 m in PSP-26-001 at approximately 77 m vertical depth.
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Drilling also intersected significant intervals of the prospective siliceous sandstone unit, confirming its presence
within the target area and providing additional information to refine the geologic model. Based on preliminary
observations to date, the siliceous sandstone is believed to represent a more favourable host for mineralization than
the calcareous sandstone (see Figure 3).
Diamond drilling at Proserpine has resumed with three active drill rigs following a brief, planned seasonal hiatus.
Additional drill rigs may be mobilized as warranted as the planned drill program continues to expand the
mineralized footprint and increase drillhole density at Proserpine Southeast, while initiating first -pass drilling at
previously untested targets at Proserpine Northwest.
FIGURE 2: Cariboo Gold regional overview.
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FIGURE 3: Plan view of Proserpine diamond drilling with select intercept highlights.
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FIGURE 4: Proserpine diamond drilling select intercept highlights in long section.
TABLE 1: Select manual composite and individual sample highligh ts greater than or equal to 1.0 g/t Au.
Drillhole ID From (m) To (m) Length (m) Au g/t Est. True
Width (m)
Approx.
Vertical
Depth (m)
PSP-26-001 71.50 72.15 0.65 1.16 0.42 55
79.70 83.60 3.90 1.18 2.95 62
Including 80.20 81.30 1.10 2.71
and 83.05 83.60 0.55 1.67
97.00 105.60 8.60 5.46 6.51 77
Including 97.50 98.20 0.70 5.97
and 98.20 99.00 0.80 5.21
and 100.73 101.60 0.87 12.50
and 101.60 102.70 1.10 16.05
and 102.70 103.20 0.50 10.25
and 103.20 104.10 0.90 1.50
and 104.10 105.00 0.90 1.18
and 105.00 105.60 0.60 3.36
146.40 147.10 0.70 1.49 0.35 112
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Drillhole ID From (m) To (m) Length (m) Au g/t Est. True
Width (m)
Approx.
Vertical
Depth (m)
165.95 166.70 0.75 1.60 0.58 126
288.95 289.60 0.65 1.23 0.56 219
290.45 290.95 0.50 1.11 0.45 220
297.80 300.90 3.10 4.30 2.46 226
Including 297.80 298.30 0.50 7.54
and 300.40 300.90 0.50 18.75
304.70 309.85 5.15 2.93 3.95 233
Including 304.70 305.65 0.95 15.60
312.70 313.25 0.55 1.21 0.42 237
334.80 335.30 0.50 1.74 0.38 254
343.95 344.45 0.50 3.98 0.32 261
494.70 495.20 0.50 3.04 0.41 376
559.85 562.35 2.50 1.04 2.11 420
Including 561.85 562.35 0.50 4.53
572.00 586.45 14.45 2.17 11.80 431
Including 574.25 574.75 0.50 1.21
and 574.75 575.25 0.50 2.21
and 577.55 578.20 0.65 35.10
and 585.45 585.95 0.50 8.61
591.50 593.00 1.50 1.10 0.96 440
PSP-26-002 15.50 16.00 0.50 1.00 0.38 12
36.60 37.20 0.60 2.57 0.39 26
47.00 47.50 0.50 3.25 0.32 34
52.10 52.60 0.50 1.20 0.35 37
73.50 74.50 1.00 2.54 0.82 52
Including 74.00 74.50 0.50 4.68
89.70 90.20 0.50 2.83 0.35 63
95.10 95.60 0.50 1.04 0.25 67
165.90 166.40 0.50 1.33 0.25 115
179.60 180.10 0.50 1.61 0.46 124
194.20 194.95 0.75 1.83 0.61 134
PSP-26-003 83.60 84.10 0.50 2.98 0.35 66
145.15 145.65 0.50 2.58 0.39 113
169.35 171.25 1.90 4.93 1.34 133
Including 170.20 170.75 0.55 16.15
183.00 184.00 1.00 1.20 0.77 144
Including 183.00 183.50 0.50 2.27
187.50 191.00 3.50 1.12 2.76 148
Including 187.50 189.00 1.50 1.17
and 190.00 190.50 0.50 3.45
294.10 299.60 5.50 1.03 4.13 235
Including 299.10 299.60 0.50 8.10
329.00 334.00 5.00 1.10 3.97 262
Including 331.25 331.75 0.50 7.78
367.00 379.40 12.40 1.46 10.31 295
Including 370.50 371.50 1.00 15.40
and 373.60 374.10 0.50 2.02
395.80 396.30 0.50 1.18 0.38 313
411.10 417.70 6.60 1.09 5.07 326
Including 412.10 412.60 0.50 1.05
and 412.60 413.10 0.50 1.11
and 413.10 413.60 0.50 6.22
and 413.60 414.20 0.60 1.89
and 415.20 415.70 0.50 1.47
and 415.70 416.20 0.50 1.32
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Drillhole ID From (m) To (m) Length (m) Au g/t Est. True
Width (m)
Approx.
Vertical
Depth (m)
419.20 420.30 1.10 1.07 0.60 330
Including 419.70 420.30 0.60 1.80
and 430.10 430.60 0.50 2.30 0.09 338
439.30 442.20 2.90 1.00 2.33 345
Including 439.30 440.00 0.70 1.04
and 440.50 441.15 0.65 2.68
and 474.90 475.40 0.50 2.26 0.32 368
478.50 479.00 0.50 1.53 0.43 370
505.85 506.35 0.50 1.53 0.41 386
533.50 534.00 0.50 6.14 0.29 402
PSP-26-004 110.40 115.00 4.60 95.93 3.25 71
Including 112.30 112.80 0.50 873.00
and 113.80 115.00 1.20 3.77
PSP-26-005 55.05 58.60 3.55 1.08 1.91 42
Including 55.05 55.60 0.55 4.67
and 58.10 58.60 0.50 2.33
76.85 79.05 2.20 3.11 1.07 59
Including 77.35 78.00 0.65 2.77
and 78.00 79.05 1.05 4.58
and 135.35 135.85 0.50 1.05 0.45 101
194.00 194.50 0.50 1.12 0.32 147
227.60 228.20 0.60 1.10 0.10 172
241.50 242.00 0.50 1.24 0.26 182
294.00 294.50 0.50 2.17 0.45 224
312.75 313.75 1.00 1.03 0.89 239
Including 312.75 313.25 0.50 1.04
and 313.25 313.75 0.50 1.02
320.00 321.00 1.00 1.33 0.94 244
402.40 402.90 0.50 1.17 0.43 306
412.20 413.30 1.10 1.43 0.72 314
Including 412.20 412.80 0.60 1.82
414.50 416.45 1.95 1.04 1.05 315
Including 415.75 416.45 0.70 2.34
522.30 523.20 0.90 1.63 0.52 384
PSP-26-006 139.70 140.20 0.50 1.05 0.45 104
161.00 161.50 0.50 1.16 0.29 121
251.60 252.10 0.50 20.20 0.35 194
293.60 294.60 1.00 10.21 0.77 227
Including 293.60 294.10 0.50 20.30
315.50 316.50 1.00 1.82 0.94 243
Including 316.00 316.50 0.50 3.36
and 323.50 324.00 0.50 1.86 0.35 249
468.50 470.00 1.50 4.86 1.27 361
Including 468.50 469.00 0.50 11.50
and 469.50 470.00 0.50 3.06
476.50 477.00 0.50 1.33 0.43 366
499.00 499.50 0.50 1.22 0.43 383
509.90 510.90 1.00 1.15 0.42 392
Including 510.40 510.90 0.50 1.41
513.70 514.50 0.80 2.25 0.34 395
PSP-26-007 25.80 30.30 4.50 2.30 3.95 17
Including 25.80 26.30 0.50 1.73
and 27.30 27.80 0.50 5.62
and 29.30 29.80 0.50 12.25
and 29.80 30.30 0.50 1.09