The Côté Gold Project is a joint venture between the IAMGOLD Corp., as operator, and Sumitomo Metal Mining Co., Ltd.
IAMGOLD announced that effective November 30, 2024, it has exercised the right to repurchase the 9.7% interest of the Côté Gold Mine that was transferred to Sumitomo Metal Mining Co., Ltd. through the amended Côté Gold Joint Venture Agreement announced on December 19, 2022. This transaction returns IAMGOLD to its full 70% interest in Côté Gold.
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Summary:
The Cote (Côté) Project mining leases area, which hosts both the Côté and Gosselin deposits, contains calc alkalic pyroclastic metavolcanic rocks of felsic to intermediate composition, felsic to intermediate intrusive rocks (predominantly tonalite and diorite) of the Chester Intrusive Complex (CIC), and related migmatites. The texture varies from granular to porphyritic, while in other areas it has the appearance of a quartz porphyry phase of the granite.
The Côté deposit is a new Archean low grade, high tonnage gold (± copper) discovery. It is described as a synvolcanic intrusion related and stockwork disseminated gold deposit. Deposits of this type are commonly spatially associated with and/or hosted in intrusive rocks. They include porphyry copper-gold, syenite associated disseminated gold and reduced gold-bismuth-tellurium-tungsten intrusion related deposits, as well as stockwork disseminated gold.
The Gosselin deposit, similar to the Côté deposit, is also hosted in the synvolcanic CIC and most of its mineralization lies within hydrothermal breccia, diorite breccia, and tonalite units. Both the Gosselin deposit and the Côté deposit are classified as intrusion related disseminated gold deposits. Preliminary investigations completed on host breccias of the Côté deposit and the Gosselin deposit reveal that the Gosselin breccias resulted from fracturing and infiltration of fluids via fractures and veins. It is postulated that the combination of fracturing and fluid infiltration resulted in intense alteration through extensive fluid wall rock interaction, resulting in the formation of the breccia type appearance
The Côté and Gosselin deposits are located with 1.5 km of each other and are both hosted by the CIC. The deposits are similar in geological composition with a few key differences in terms of breccia rocks and alteration. Both deposits are centred on magmatic and hydrothermal breccia bodies that intrude tonalitic and dioritic rocks. The CIC intruded into the mafic volcanic rocks of the Arbutus Formation, which forms the basal formation in the Chester Group. The formation consists of low potassium tholeiitic pillow basalts, mafic flows, and sills. The intrusive host rocks formed from a number of pulses of several distinct and evolving dioritic and tonalitic magmas that display complex crosscutting relationships.
The Côté and Gosselin deposit type gold mineralization consists of low to moderate grade gold (±copper) mineralization associated with brecciated and altered tonalite and diorite rocks. Several styles of gold mineralization are recognized within the deposits, and include disseminated, breccia hosted and vein type, all of which are co-spatial with biotite (± chlorite), sericite and for the Côté deposit silica-sodic alteration. Disseminated mineralization in the hydrothermal matrix of the breccia is the most important style of gold (±copper) mineralization. This style consists of disseminated pyrite, chalcopyrite, pyrrhotite, magnetite, gold (often in native form), and molybdenite in the matrix of the breccia and is associated with primary hydrothermal biotite and chlorite after biotite. In contrast, disseminated biotite and chlorite (after biotite) alteration are not typically associated with gold mineralization. When present, however, disseminated gold and chalcopyrite are intergrown with biotite–chlorite in the Côté deposit. Disseminated mineralization is typically associated with sericite alteration within the Gosselin deposit or silica-sodic alteration within the Côté deposit.
The nature of the veins and fractures vary from stockworks to closely spaced, planar, subparallel sheeted vein sets. Stockwork mineralization cuts through all major rock types but is most prominent in the more brittle tonalitic phases compared to the dioritic phases and formed during the biotite alteration event. The mineralized sheeted veins and stockwork zones cut the hydrothermal breccia and therefore post-date the breccia-controlled mineralization. Miarolitic-like cavities, which are common within the Côté deposit but not observed within the Gosselin deposit, consist of millimetre to centimetre size openings lined with feldspar, carbonate, and sulphide, and can also contain gold. Importantly, the gold bearing sheeted veins have been observed to be syn-intrusion in timing based on a structural study in the Côté deposit area. In addition, Re-Os molybdenite dating of one of these gold bearing veins returned an age of 2,746.8 ± 11.4 Ma, which overlaps with the age of the intrusive events.
The hydrothermal breccia and associated hydrothermal alteration zones are the material component of the mineralization providing the mineable widths and grades to the deposits. Areas outside of its significant development are likely not a significant contribution to economically important mineralization.
The various gold bearing quartz vein systems, also observed immediately adjacent to the proposed open pit, serve to upgrade the hydrothermal envelope where they are present. The amount of gold contributed by these quartz vein systems to the deposits is difficult to determine but is thought to be of some significance to overall metal content.
Commodity Production
In 2024, Côté produced 124,000 attributable ounces (199,000 ounces on a 100% basis) during its initial nine months of operation.
| Commodity | Product | Units | 2025 | 2024 |
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Gold
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Metal in doré
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koz
| .... | .... |