Boto Project

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Mine TypeOpen Pit
  • Gold
Mining Method
  • Truck & Shovel / Loader
Production Start... Lock
Mine Life... Lock
SnapshotBoto Gold Project is currently at the construction phase, the plant commissioning scheduled for H1 2025.

Part of the infrastructure including camps, access road and utilities is operational. Pre-stripping of the main pit Malikoundi started in 2024.


Government of Senegal 10 % Indirect
Managem SA 90 % Indirect
On December 20, 2022, IAMGOLD announced that it had entered into definitive agreements with Managem to sell the Boto Gold Project.

On April 25, 2023, the IAMGOLD completed the sale of its 90% interest in the Boto Gold Project. The remaining 10% of Boto will continue to be held by the Government of Senegal.



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Deposit type

  • Vein / narrow vein
  • Orogenic


The Project consists of four (4) deposits, Malikoundi/Boto 2, Boto 5, Boto 4 and Boto 6, all of the late orogenic type.

Boto can be divided into three north trending litho-structural domains (020° N) that are well delineated in both induced polarization (IP) and magnetic surveys. From west to east, the three domains are:
• Western Flyschoid Domain.
• Central Deformation Corridor.
• Eastern Siliciclastic Domain.

Malikoundi/Boto2, Boto 4, and Boto 6.
At Malikoundi/Boto 2, Boto 4 and Boto 6, the regolith is composed of pedolith (soil, ferricrete, and laterite), saprolite, and transition weathering profiles (saprock) that average 8 m, 20 m, and 10 m in thickness, respectively. The detailed study of regolith has made it possible to distinguish between transported and in-situ regolith. The assay results from up-dip expressions of mineralized zones, confirm in-situ mineralized regolith. Mineralization in fresh rock is mainly associated with pervasive albite alteration and pyrite.

Interpretation of structural data collected from oriented drill core has shown differences between Malikoundi/Boto 2, Boto 4, and Boto 6. Boto 6 is characterized by a bedding strike of 025° N, whereas Malikoundi/Boto 2 appears to have two bedding strike directions of 015° N and 030° N. The two bedding strike directions observed at Malikoundi/Boto 2 may result from ductile deformation within the impure marbles and laminated detrital sediments. Contrary to other parts of the structural corridor, a significant rotation of bedding strike to 147° N is noted in the drill core at Boto 4.

At Malikoundi/Boto 2, a 30° to 60° westward- dipping thrust fault has been observed in drill core at the contact between the Guémédji sandstone and the sequence of marble/laminated sediments. Of particular interest is a large lens of Guémédji sandstone that lies above the fault. This over-riding block of sandstone from the north end, cut out and moved from the Guémédji sandstone unit, is the main host of mineralization in this prospect. As a result of these movements, this lenticular block was severely fractured against adjacent rocks, and this fracturing was the conduit through which the gold-carrying fluids circulated and the mineralization was deposited. Thus, the fracturing associated with the sandstone lens is the principal carrier of mineralization in facies as diverse as sandstone, pelites, agglomerates, cipolin (unclean marble), or sometimes even syntectonic diorite. This overlap/shear fault was also identified further south in Boto 4 and Boto 6, further north of the Falémé River to the Fekola Gold Mine in Mali (called Medinandi permit), owned and operated by B2Gold; as well as further south to the Tammy permit (Mali). Several different units of cipolin were observed and these units played the role of deformation trends as well as permeability barriers to mineralizing fluids. At Malikoundi North, one of the units of cipolin corresponds to the mineralization zone having accommodated the deformation related to the circulation of mineralizing fluids.

Cipolin units can be subdivided into:
• Stratigraphic Cipolin In-situ: these marbles are distorted but remain in their stratigraphic place and are generally thick.
• Cipolin of Re-crystallized Deformation: these marbles are very distorted and re-crystallized and have been spread along shear structures by deformation. They no longer correspond to the stratigraphic orientation, but to a structural orientation usually making the junction between two different stratigraphic cipolins that were thus accommodated; their thickness is generally low, with an average thickness between 2-3 m and only rarely surpassing 10-15 m.

Boto 5.
The weathering profile of Boto 5 is considerably deeper than that of Malikoundi/Boto 2, Boto 4 and Boto 6. Boto 5 is covered with a layer of pedolith 10 m to 40 m thick under which the saprolite layer can reach up to 80 m thick. The transitional layer under the saprolite is between 10 m to 40 m thick.

The lithological units at Boto 5 strike 015°-020° and include shale, carbonaceous sediment, and basalt. An albitealtered diorite dike that hosts the mineralization at Boto 5 cross-cuts the stratigraphy, striking 045° N dipping between 45° W and 60° W towards the west, approximately 30 m wide, and containing fragments of host rock in places.Four deformation phases occurred at Boto 5. An early phase of brittle-ductile deformation led to the emplacement of barren tourmaline veins. This was followed by reverse brittle-ductile faulting overprinted and reactivated on the northeast trending structures. Gold-bearing quartz-tourmaline veins were formed during this phase. The D2 structures were subsequently covered by a third ductile deformation phase. The latest deformation event is characterized by north-northwest and northeast trending brittle faults that offset the mineralization into blocks.

Similar to the majority of the deposits found in the Kédougou-Kéniéba inlier, gold mineralization at Boto is considered to be of the orogenic type. The orogenic gold deposits in the Birimian Province have been classified into three groups (Pre-, Syn-, and Post-orogenic). The characteristics of Boto mineralization are more similar to those of the post orogenic class.

The Malikoundi/Boto 2, Boto 4 and Boto 6 deposits are hosted by a turbiditic sedimentary sequence, with mineralization concentrating along the contacts of the litho-structural domains. The association of orogenic deposits with turbiditic sequences is well documented by Poulsen et al. (2000). Turbidite-hosted gold deposits within the eastern Kédougou-Kéniéba inlier are controlled by north-northeast trending structures linked to the SMSZ and, occur within the vicinity of intersecting north-northeast and north-north-west structures. At the Malikoundi/Boto 2, Boto 4 and Boto 6 deposits, gold is typically associated with pyrite, which is either disseminated along fractures (crackle-breccia hosted type) or along brittle-ductile veins.

Alteration assemblages observed at Boto 5 differ from those observed at Malikoundi/Boto 2, Boto 4, and Boto 6. The Boto 5 deposit is hosted in a diorite dike that contains abundant endogenic albite or has been pervasively altered to albite. The host rock at Boto 5 is highly deformed and contains a stockwork of quartztourmaline-pyrite veins. Although differing in appearance, this style of brittle- ductile deformation and veining is consistent with an orogenic gold mineralization model.



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CommodityUnitsAvg. AnnualLOM
All production numbers are expressed as metal in doré.

Operational metrics

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* According to 2020 study.

Production Costs

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* According to 2020 study / presentation.

Operating Costs

OP mining costs ($/t milled) USD 16.8 *  
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* According to 2020 study.

Project Costs

MetricsUnitsLOM Total
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OP OpEx $M USD  ......  Subscribe
Processing OpEx $M USD 396
G&A costs $M USD 108
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Mine Management

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