IAMGOLD Corporation (“IAMGOLD” or the “Company”) announces assay results from its 2021 exploration diamond drilling program completed on the Lac Gamble zone at the Rouyn Gold project (“Rouyn Project”) optioned from Yorbeau Resources Inc. (“Yorbeau”). The project is located 4 km south of Rouyn-Noranda, Québec, and approximately 45 kilometers southwest of IAMGOLD’s Westwood operation.

The Company is reporting assay results from seven (7) diamond drill holes, totaling 1,826 metres completed as part of the winter 2021 drilling program. Drilling activities are also currently progressing on the Augmitto and Cinderella areas, located approximately 1 to 3 kilometres west of the Lac Gamble zone, and results will be reported when received, validated and compiled. The assay results reported herein are provided in Table 1, below, and include the following highlights (a longitudinal section illustrating the drilling program on the Lac Gamble zone is attached to this news release):

Craig MacDougall, Executive Vice President, Growth, IAMGOLD, stated: “Our drilling program at Lac Gamble earlier this year specifically targeted some selected areas for possible extensions, as well as to complete some initial geotechnical drill holes to assess rock quality in the context of a potential underground mining scenario. The results continue to strengthen our understanding of the deposit geology and geotechnical rock quality appears in line with our expectations from the initial assessment. Despite the recent challenges faced by a shortage of available drilling rigs in the region, we continue to make solid progress in our project evaluation.”

The diamond drilling program on the Lac Gamble zone had two main objectives: 1) complete an initial geotechnical drilling campaign to collect preliminary data to assess rock quality of the host rock units with respect to an underground mining method; and, 2) test for potential extensions down plunge along the western boundary of the zone. The geotechnical drill program consisted of four (4) holes for 720.5 metres and the data obtained appears to be in line with the anticipated geotechnical conditions to support a potential underground mining development scenario.

The expansion drilling program targeted potential down-plunge extensions to the west for which three (3) diamond drill holes totaling 1,105 metres were completed. Unfortunately, due to the late start of the drilling program caused by a regional lack of drill rig availability, a planned larger program could not be completed during the optimal winter season. All drill holes successfully intersected the targeted sheared Cadillac- Piché corridor, which hosts the mineralized Lac Gamble zone. The zone is associated with alteration varying from several metres to greater than 10 metres in width, exhibiting variable carbonatization, fuchsite, silicification, crosscut by a network of white quartz and brown tourmaline stockwork veins and breccias. Gold mineralization occurs as small specks of visible free gold associated with minor sulphides in quartz-tourmaline veinlets. Hole GA-21-782 has demonstrated the zone could extend further in its western extensions at depth.

Next Steps

The ongoing global COVID-19 pandemic continues to impact the local availability of exploration services. However, exploration drilling has resumed at the Rouyn Project in June and a planned 9,000 metre diamond drilling program is in progress to evaluate the resource potential of other selected targets, including the Cinderella and Augmitto areas located further west of the Lac Gamble zone and if timing permits to the east at the Astoria east zone.

The assay results from the drilling programs will be integrated with the existing geological, geochemical and structural information to support the development and refinement of preliminary deposit models on the property to support a future potential maiden resource estimate.