IAMGOLD Corporation press release

IAMGOLD Drilling Extends Mineralization at Nelligan, Intersects High-Grade Gold at Monster Lake and Advances Philibert Within Its Nelligan Mining Complex

2026-10-27

TSX - Toronto Stock Exchange · Gold · Canada · Drill Results

All monetary amounts are expressed in U.S. dollars, unless otherwise indicated.

Toronto, Ontario--(Newsfile Corp. - October 27, 2026) - IAMGOLD Corporation(NYSE: IAG) (TSX: IMG) ("IAMGOLD" or the "Company") is pleased to announce assay results from its ongoing 2025-2026 drilling programs at the Nelligan Mining Complex (100% owned by IAMGOLD). The results confirm the depth extension of the mineralized zones at Nelligan, Monster Lake and Philibert, and define existing resources with closer-spaced drilling at all three deposits. Nelligan, Philibert and Monster Lake are located within a 15 km radius, and the combined exploration camp is accessible by road approximately 60 km southwest of Chibougamau in central Quebec, Canada.

"I congratulate our exploration team on an outstanding campaign across the Nelligan Mining Complex. Drilling continues to extend the mineralized system at depth at Nelligan, while also delivering compelling high-grade intersections at Monster Lake and strong results from our inaugural program at Philibert," said Renaud Adams, President and Chief Executive Officer of IAMGOLD. "Through the consolidation of Nelligan, Monster Lake and Philibert, we have created one of Canada's largest pre-production gold camps, and these results reinforce the scale, quality and growth potential of the Complex. We look forward to providing our next exploration update in the first half of 2027, followed by a Preliminary Economic Assessment that will outline the potential for the Complex to become one of IAMGOLD's premier assets. Wholly owned by IAMGOLD and situated in a stable, mining-friendly jurisdiction, the Complex offers an attractive avenue for organic growth and further strengthens our pipeline as a leading intermediate gold producer."

Nelligan Drilling Highlights

Zone 36:

77.0 metres ("m") at 2.23 grams per tonne gold ("g/t Au"),including 1.5 m at 13.9 g/t Au, 6.0 m at 7.14 g/t Au and 1.5 m at 9.37 g/t Au in hole NE-26-272; 25.15 m at 4.02 g/t Au, including 1.5 m at 15.0 g/t Au and 1.25 m at 12.0 g/t Au, 29.15 m at 2.18 g/t Au, including 2.15 m at 6.54 g/t Au and 1.2 m at 9.69 g/t Au,and 21.65 m at 2.48 g/t Au,including 5.0 m at 6.20 g/t Au in hole NE-26-288A; 48.05 m at 1.84 g/t Au, including 2.65 m at 5.63 g/t Au and 1.5 m at 9.0 g/t Au in hole NE-26-297. 20.5 m at 2.49 g/t Au, including 1.5 m at 15.55 g/t Au and 1.18 m at 11.3 g/t Au,and 32.0 m at 2.52 g/t Au, including 1.5 m at 16.35 g/t Au in hole NE-25-269; 8.0 m at 5.17 g/t Au, including 1.5 m at 18.7 g/t Au in hole NE-26-277A;

Renard Zone:

37.28 m at 3.62 g/t Au, including 8.5 m at 10.61 g/t Au in drill hole NE-26-297; 22.0 m at 4.47 g/t Au, including 1.0 m at 32.8 g/t Au in drill hole NE-26-288A; 54.5 m at 1.48 g/t Au, including 0.6 m at 5.92 g/t Au and 1.3 m at 11.7 g/t Au in drill hole NE-26-277A; 37.0 m at 1.90 g/t Au, including 1.5 m at 5.85 g/t Au and 1.5 m at 5.72 g/t Au in drill hole NE-26-302A; 13.5 m at 4.25 g/t Au, including 3.0 m at 15.7 g/t Au, and 29.5 m at 1.27 g/t Auin drill hole NE-26-303.

Footwall Zone:

7.5 m at 14.37 g/t Au,including 3.0 m at 33.8 g/t Au in drill hole NE-25-266; 7.5 m at 7.41 g/t Au, including 1.5 m at 33.6 g/t Au in drill hole NE-25-270A; 12.0 m at 3.25 g/t Au, including 2.0 m at 10.45 g/t Au and 1.5 m at 8.23 g/t Au in drill hole NE-26-271A; 51.0 m at 1.16 g/t Au, including 1.5 m at 9.68 g/t Au in drill hole NE-26-297; 29.5 m at 1.38 g/t Auin drill hole NE-26-303.

Dan Zone:

12.5 m at 4.76 g/t Au, including 1.8 m at 12.0 g/t Au and 1.2 m at 19.9 g/t Au in hole NE-26-288; 13.4 m at 5.20 g/t Au, including 1.5 m at 9.14 g/t Au in hole NE-26-294.

Monster Lake Drilling Highlights:

Megane Zone (in the Main Shear Zone):

7.3 m at 49.6 g/t Au,including 1.0 m at 155.6 g/t Au in drill hole ML-26-318; 10.35 m at 22.99 g/t Au,including 5.0 m at 37.8 g/t Au, including 1.0 m at 144.6 g/t Au in drill hole ML-26-302; 9.45 m at 21.16 g/t Au, including 2.35 m at 80.5 g/t Au, including 0.85 m at 128.8 g/t Au in drill hole ML-26-314A; 12.2 m at 14.71 g/t Au, including 5.6 m at 25.04 g/t Au, including 1.0 m at 51.3 g/t Au in drill hole ML-26-300; 9.8 m at 11.02 g/t Au,including 0.8 m at 54.8 g/t Au in drill hole ML-26-317; 5.5 m at 18.69 g/t Au,including 0.75 m at 79.0 g/t Au in drill hole ML-26-320. 3.25 m at 21.61 g/t Au, including 1.0 m at 49.9 g/t Au in drill hole ML-26-312;

Megane Zone depth extension (in the Main Shear Zone):

7.7 m at 24.77 g/t Au, including 1.0 m at 86.8 g/t Au and 1.0 m at 81.1 g/t Au in drill hole ML-25-293; 7.5 m at 10.52 g/t Au, including 2.75 m at 25.1 g/t Au, including 1.0 m at 54.0 g/t Au in drill hole ML-25-296.

Philibert Drilling Highlights:

Red Fox Zone:

20.5 m at 2.51 g/t Au, including 4.0 m at 6.20 g/t Au in drill hole PB-26-533; 14.8 m at 3.59 g/t Au, including 6.2 m at 7.11 g/t Au, and 29.4 m at 1.04 g/t Au, including 0.9 m at 6.22 g/t in drill hole PB-26-535; 26.0 m at 2.09 g/t Au, including 6.0 m at 6.33 g/t in drill hole PB-26-539. 11.5 m at 4.23 g/t Au,including 3.0 m at 15.15 g/t Au in drill hole PB-26-516; 29.5 m at 1.50 g/t Au, including 4.0 m at 3.28 g/t Au in drill hole PB-26-521; 5.6 m at 5.73 g/t Au, including 1.5 m at 18.72 g/t Au, and 16.0 m at 1.96 g/t Au, including 1.9 m at 6.11 g/t Au and 1.4 m at 7.10 g/t Au in drill hole PB-26-525; 17.5 m at 2.25 g/t Au, including 3.7 m at 3.89 g/t Au in drill hole PB-26-529; 17.5 m at 2.28 g/t Au, including 7.0 m at 4.19 g/t Au in drill hole PB-26-531;

Arctic Fox Zone:

11.9 m at 6.05 g/t Au,including 6.0 m at 8.15 g/t Au in drill hole PB-26-561; 14.0 m at 2.54 g/t Au,including 1.1 m at 9.31 g/t Au in drill hole PB-26-557; 4.5 m at 6.78 g/t Au,including 1.0 m at 18.8 g/t Au in drill hole PB-26-563; 4.5 m at 7.04 g/t Auin drill hole PB-26-575.

Arctic Fox depth extension:

29.3 m at 3.39 g/t Au,including 2.8 m at 8.06 g/t Au, 5.9 m at 5.66 g/t Au and 4.0 m at 6.45 g/t Au in drill hole PB-26-581. 6.0 m at 4.34 g/t Au,including 2.0 m at 8.51 g/t Au in drill hole PB-26-580;

Marie-France Bugnon, Vice President, Exploration for IAMGOLD, commented: "Results from our ongoing exploration programs at the Nelligan Mining Complex are very encouraging and support our objective of expanding the mineralized envelopes of all three deposits. At Nelligan, mineralization continues down plunge, with several intersections grading well above the current Mineral Resource average. We will continue infill drilling while advancing step-out drilling to further extend the system. At Monster Lake, recent drilling has returned high-grade intersections and extended the Megane Zone to a depth of 600 metres. Based on the mineralization style and structural controls, we plan to advance delineation drilling. At Philibert, our first drilling program confirmed previously defined zones and grades, increasing our confidence in the upcoming Mineral Resource estimate and indicating additional potential at depth. I also warmly congratulate the exploration team for safely executing these programs and for their continued commitment to delivering strong results."

NELLIGAN DRILLING PROGRAM RESULTS

IAMGOLD is reporting assay results from 47 diamond drill holes totaling 20,641 metres completed as part of the ongoing drilling program on Nelligan. These drill holes were completed between June 2025 and June 2026. This total includes 35 infill holes completed within the resources shell, seven deeper exploration holes testing the extension of the Nelligan deposit down-plunge at depth and five exploration holes drilled outside the resources area on exploration targets. Few of the infill and deeper holes were recollared due to excessive deviation. Please refer to the three longitudinal sections for drill hole locations that intersect Zone 36, Renard and Footwall zones outlined in Figures 1 to 3 below. In addition, the full assay results are provided in Table 1 at the end of this news release.

[](https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_001full.jpg)

Figure 1 - Nelligan Vertical Long section through the Zone 36

To view an enhanced version of this graphic, please visit: https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_001full.jpg

The diamond drilling programs were designed to expand the deposit at depth and to the south below Zone 36, alongside with in-fill drilling to improve resource classification. Selected areas were targeted including the shallow eastern extension of the deposit best accessed via an ice platform during the winter. Winter conditions were also used to support infill drilling in the Dan Zone. Mineralization associated with the estimated Mineral Resources has been intersected over a strike length of more than 1.8 kilometres and to a depth of 600 vertical metres. The mineralized system of Renard remains open at depth.

[](https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_002full.jpg)

Figure 2 - Nelligan Vertical Long section through the Renard Zone

To view an enhanced version of this graphic, please visit: https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_002full.jpg

[](https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_003full.jpg)

Figure 3 - Nelligan Vertical Long section through the Footwall Zone

To view an enhanced version of this graphic, please visit: https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_003full.jpg

Next Steps

With the additional results disclosed, the 2025 and 2026 diamond drilling programs have successfully extended the Nelligan deposit further down-plunge to the East (below the 600 metres vertical depth) with the persistence and increasing widths of the typical mineralized sequence intersected in most holes. Notably this drilling may extend further south Zone 36 which was not systematically drilled below the 300-350 metres vertical level. These results are currently incorporated into the deposit model and will support the updated Mineral Resource estimate targeted for the end of this year.

The initial diamond drilling program for 2026 was planned for 18,000 metres but has been expanded to a total of 30,000 metres. The additional drilling is mainly dedicated to infill drilling for resources conversion from the Inferred Resources to the Indicated Resources category to improve resources classification. Step-out drilling to test the deeper extensions of the mineralized zones will be considered for 2027 and technical studies will continue to advance such as metallurgical testing and other engineering studies.

Regional exploration activities and future exploration programs will continue and will be guided by the ongoing incorporation and compilation of field exploration data to refine geological, geochemical and structural models to help identify and prioritize additional targets for evaluation on the larger project land package.

About the Nelligan Deposit

Nelligan is a large-scale open pit gold exploration project fully owned by IAMGOLD. Nelligan has shown strong growth potential with recent drilling confirming significant extensions of gold-bearing zones, particularly in the Renard, Footwall, and Zone 36 areas.

The Nelligan project is underlain by a portion of the Caopatina segment of the North Volcanic Zone of the Abitibi Belt of the Superior Province. The property is centered on the E-W Druillettes syncline with sediments of the Caopatina Formation bounded to the north and to the south by volcanic rocks of the Obatogamau Formation. The North and South portions of the property are occupied by granodioritic to tonalitic intrusions. The project is transected by numerous regional and local structures and deformation zones which can be important in the localization of gold mineralization.

Gold showings of the area are observed broadly as two styles of mineralization: 1) Quartz-sulphide vein type, and 2) disseminated sulphide (pyrite) mineralization in hydrothermally altered units. Mineralization observed on the Nelligan deposit is dominated by the latter and is characterized by hydrothermal alteration of the host volcano-sedimentary units displaying variable carbonatization, sericite, phlogopite and pervasive silicification; and associated with widespread disseminated pyrite, varying from 1% to locally 15%, trace molybdenite and occasionally fine grains of visible gold.

As of December 31, 2025, estimated Mineral Resources at the Nelligan deposit are comprised of 122.0 million tonnes of Indicated resources grading 0.95 grams of gold per tonne for 3.7 million ounces of contained gold and 151.0 million tonnes of Inferred resources grading 0.96 grams of gold per tonne for 4.6 million ounces of contained gold.

Open-Pit Mineral Resources (at 0.35 g/t Au cut-off)

| Mineral Resources Statement - Nelligan Project As of December 31, 2025 | | | | | Classification | Tonnes (000s) | Grade (g/t Au) | Ounces (000s) | | Total Indicated | 122,000 | 0.95 | 3,700 | | Total Inferred | 151,000 | 0.96 | 4,647 |

MONSTER LAKE DRILLING PROGRAM RESULTS

IAMGOLD is also reporting assay results from 41 diamond drill holes totaling 18,136 metres completed as part of the late 2025 and the ongoing 2026 Monster Lake Resources Area drilling program. These drill holes were completed between June 2025 and May 2026. This total includes 22 infill holes completed in the resources block model, twelve deeper exploration holes testing the extension of the Megane Zone, and seven holes on exploration targets. Of the twelve deeper holes, two were wedge cuts from master holes and two were recollared due to excessive deviation, and a few of the exploration holes were also recollared due to excessive deviation. Please refer to the longitudinal section for drill hole locations in Figure 4. In addition, the full assay results are provided in Table 2 at the end of this news release.

[](https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_004full.jpg)

Figure 4 - Monster Lake Long Vertical Cross Section

To view an enhanced version of this graphic, please visit: https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_004full.jpg

The 2026 Monster Lake diamond drilling program was designed to infill the top portion of the Megane Zone to increase confidence in the existing resource and grade, and to expand the potential resources at depth by testing further the Megane Zone extensions following positive results obtained from the 2025 drilling. All holes have intersected the Main Shear Zone that hosts the Megane Zone and few other zones in its south (Zone 52) and North (Big Mama area) extensions.

Next Steps

The drilling program will continue at depth and along strike in areas where drill hole spacing remains too wide, especially directly to the North of the existing resources. These areas will be progressively evaluated along the most prospective areas of the Monster Lake Shear Zones and its secondary associated structures. Exploration field activities results are continuously compiled to refine the geological and structural model to help identify and prioritize various regional targets developed from targeting exercises to guide future drilling programs. The Company is evaluating the potential development of an exploration ramp from surface to provide underground drill platforms for more effective testing of the Monster Lake deposits.

About the Monster Lake Project

Monster Lake, located 15 kilometres north of Nelligan, is a high-grade underground gold project with a focus on the Megane Zone.

The Monster Lake project is underlain by Archean volcanic rocks of the Obatogamau Formation, which are traversed by an important deformation corridor with associated gold-bearing mineralized structures and dyke swarms. Exploration to date has traced this prospective structural shear zone system for at least 4 kilometres along strike, along which several gold prospects have been discovered, and a Mineral Resource has been delineated at the Megane Zone.

The gold zones observed at Monster Lake are typically of orogenic style with mineralization mostly associated with smokey quartz veins (grey to black) with free gold and sulphide minerals in the sheared wall rocks (pyrite, pyrrhotite, chalcopyrite and sphalerite).

As of December 31, 2025, the updated Mineral Resources for Monster Lake comprises 243,000 tonnes of Indicated Mineral Resources averaging 13.0 g/t Au for 102,000 ounces of gold, and 1,046,000 tonnes of Inferred Mineral Resources averaging 14.8 g/t Au for 499,000 ounces of gold for an underground mining scenario.

Underground Mineral Resources (at 4.1 g/t Au cut-off)

| Mineral Resources Statement - Monster Lake Project As of December 31, 2025 | | | | | Classification | Tonnes (t) | Grade (g/t Au) | Ounces (oz Troy Au) | | Total Indicated | 243,000 | 13.0 | 102,000 | | Total Inferred | 1,046,000 | 14.8 | 499,000 |

PHILIBERT DRILLING PROGRAM RESULTS

IAMGOLD is reporting assay results from 65 diamond drill holes totaling 18,309 metres as part of the ongoing 2026 Philibert drilling program. These drill holes were completed between January and June 2026. This total includes 63 infill holes completed in the resources block model, and two deeper holes testing the down plunge of the Arctic Fox Zone. Please refer to the longitudinal section for drill hole locations in Figure 5. In addition, the full assay results are provided in Table 3 at the end of this news release.

The 2026 Philibert diamond drilling program was designed to first infill the shallow parts of the Red Fox and Arctic Fox Zones that are not easily accessible during the summertime and to test depth extensions. The results of the infill program indicate good continuity and grade of what was previously delineated. The two deeper holes in the down plunge of the Arctic Fox Zone are very encouraging to further expand the potential of this deeper zone.

Next Steps

This year, a diamond drilling program of a minimum of 20,000 metres was originally planned, and the target was increased to 30,000 metres as summer ground conditions allowed additional drilling to test some deeper prospective zones. Approximately 28,000 metres were completed at the end of the third quarter.

The 2026 drilling program aimed primarily to convert a significant portion of the Inferred Resource to the Indicated Resource category. These results are currently incorporated into the deposit model and will support updated Mineral Resource estimate targeted for the end of this year. Next year's program will consider field verifications and exploration drilling on other prospective targets in the project area.

[](https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_005full.jpg)

Figure 5 - PhilibertLong Vertical Cross Section

To view an enhanced version of this graphic, please visit: https://images.newsfilecorp.com/files/6077/320988_bcbb28eb84badbd5_005full.jpg

About the Philibert Project

The Philibert Project is located approximately 10 kilometres north-east of Nelligan. The project is owned 100% by IAMGOLD following the acquisition of a remaining 25% interest in the Philibert property held by SOQUEM upon completion of the acquisition of Northern Superior Resources by IAMGOLD in December 2025.

The Philibert project is underlain by Archean volcanic rocks of the Obatogamau Formation, which are traversed by the Guercheville Deformation Zone and associated gabbro sills that are variably altered and host most of the gold mineralization. On Philibert, the deformed corridor contains few 10 to 20 metres in width zones of pervasive silicification with stockwerks of quartz and quartz-carbonate veins with free gold and associated sulphides (pyrite being dominant, pyrrhotite, and traces of chalcopyrite and molybdenite).

As of December 31, 2025, the reported Mineral Resources for Philibert comprises 7,884,000 tonnes of Indicated Mineral Resources averaging 1.10 g/t Au for 279,000 ounces of gold, and 48,465,000 tonnes of Inferred Mineral Resources averaging 1.10 g/t Au for 1,709,000 ounces of gold.

Open-Pit Mineral Resources (at 0.35 g/t Au cut-off)

| Mineral Resources Statement - Philibert Project As of December 31, 2025 | | | | | Classification | Tonnes (000s) | Grade (g/t Au) | Ounces (000s) | | Total Indicated | 7,884 | 1.10 | 279 | | Total Inferred | 48,465 | 1.10 | 1,709 |