Endeavour Announces Positive PFS Results for Assafou Project in Côte d'Ivoire

ENDEAVOUR ANNOUNCES POSITIVE PFS RESULTS FOR ASSAFOU PROJECT IN CÔTE D'IVOIRE

$1,526m NPV_(5%) and IRR of 28% at $2,000/oz • 329kozpa at AISC of $892/oz over first 10 years

Ian Cockerill, CEO, commented: "I am delighted with the results of this pre-feasibility study that highlight the potential for Assafou to become a tier 1 asset for Endeavour.

We have defined a large, low-cost and long mine life project, capable of producing 330koz a year over the first ten years, while remaining firmly in the lowest cost quartile. The attractive returns profile ensures this project will remain a capital allocation priority for us and it demonstrates our ability to generate highly value accretive projects, organically, through our pipeline.

Our exploration team discovered Assafou in late 2021, and in less than three years we have defined a high-quality project with close to 5 million ounces of high-grade Indicated resource endowment. We expect that we will continue to grow the Assafou deposit's resource, and delineate several exciting near-mine targets across the wider Tanda-Iguela property.

Given the excellent project economics, we will now launch the Definitive Feasibility Study and simultaneously advance the permitting process so that we are well positioned to potentially launch construction, with our best-in-class projects team, in the second half of 2026.

With a robust pipeline of organic growth opportunities, we expect to continue to unlock value and deliver long-term production growth towards our 1.5 million ounce target, from a diversified portfolio of assets, by the end of the decade, while maintaining best-in-class margins. This underpins our capital allocation framework, and we expect to continue to deliver supplemental shareholder returns in line with our existing policy, and maintain attractive shareholder returns through this next growth phase.”

Table 1: Assafou Project Highlights

The key operational and economic highlights of the Assafou PFS are summarised in Tables 2 and 3 below.

Table 2: Assafou PFS Summary

³GHG Emissions Intensity considers only Scope 1 and 2 emissions

Table 3: Assafou PFS Project Economics

Endeavour expects to file a Technical Report pursuant to National Instrument 43-101 - Standards of Disclosure for Mineral Projects ("the NI 43-101”) in respect of the Assafou PFS within 45 days of this news release.

Overview

The 100% owned Tanda and Iguela permits ("Tanda-Iguela”) are located in the eastern region of Côte d'Ivoire, approximately 600km northeast of Abidjan, adjacent to the Ghana border. The northern permit, Tanda, was added to Endeavour's portfolio in late 2015 following Endeavour's transaction with La Mancha. Endeavour conducted an initial drilling campaign in early 2016 that yielded positive results and quickly identified the southern permit, Iguela, as having a high degree of geological prospectivity. The Iguela permit was awarded to Endeavour in May 2017, through Côte d'Ivoire's permitting application process.

Figure 1 : Tanda-Iguela Map

A maiden Indicated resource of 1.1Moz at 2.33 g/t Au was published on 21 November 2022 and was subsequently increased to 4.5Moz at 1.97 g/t Au on 29 November 2023, based on a $1,500/oz gold price.

As shown in Figure 2 below, the PFS demonstrates Assafou's ability to deliver 329kozpa at AISC of $892/oz over the first ten years of operations, with average production exceeding 350kozpa over an 8-year period once the operation is ramped up, and average production of 265kozpa and AISC of $936/oz over life of mine.

Figure 2: Assafou PFS Production and AISC Profile^1,2

¹Assafou PFS production is based on the 2024 Mineral Reserve Estimate, and does not incorporate drilling completed after November 2023, which provides significant upside to the production profile from Y-10 onwards. ²AISC based on a gold price of $2,000/oz

The PFS production profile is based on the mineral reserves only with an effective date of 31 August 2024, which are constrained by a resource with a drilling cutoff of 31 October 2023. Significant exploration drilling has been completed since this cutoff, which is expected to contribute to resource and reserve upside supporting higher levels of production, particularly in years 10 to 15 of the production profile.

Reserves and Resources

As shown in Table 4 below, the PFS mineral resource is based on the 2023 Mineral Resource Estimate ("MRE”), as published on 29 November 2023, which has been restated using a $1,900/oz gold price, compared to the $1,500/oz gold price used when it was published. The drilling cut-off for the 2023 MRE was 31 October 2023, with the MRE constituting 183,000 metres of drilling at the Assafou deposit. Subsequently, a further 70,000 metres of drilling has been completed during late 2023 and year-to-date 2024 at the Assafou deposit and satellite targets in close proximity to Assafou, which are expected to be incorporated into a future mineral resource update that will underpin the DFS.

Table 4: Assafou Reserves and Resources

The updated mineral resource estimate for the Assafou deposit comprises an Indicated resource of 73.6Mt at 1.95g/t for 4.6Moz and an Inferred resource of 3.3Mt at 1.97g/t for 0.2Moz, based on a cut-off grade of 0.5 g/t Au and a $1,900/oz gold price. The mineral resource at the Assafou deposit is robust, as it is high-grade and hosted in thick, continuous lenses, as demonstrated by the sensitivity analysis presented in Table 5 below. Inferred material within the pit design was treated as waste in the PFS.

Table 5: Assafou Mineral Resource Estimate Sensitivity¹

For technical notes and drilling results from the Assafou drill programme, please see the Technical Notes section below.

Mining Operations

The Assafou deposit mineralisation extends from surface to depths in excess of 300 metres and is amenable to conventional open-pit mining. The mine planning, resource and cost estimation for the PFS is based on a contract mining operation with a maximum mining capacity of 62.5 Mt per year. Mining capacity is expected to exceed processing capacity in order to accumulate stockpiles to allow high grade material to be preferentially processed early in the mine life. During the pre-commercial production period approximately 36.5 Mt of pre-stripping is expected to support an accelerated ramp up of the production profile. The DFS will review opportunities to reduce the impact of pre-stripping at the Assafou deposit through supplementing the ore feed with near-surface ore from the Pala Trend 3 deposit, located 1km away from Assafou.

Diesel excavators and trucks will be used for loading and haulage, with a contractor fleet expected to comprise of 300-tonne and 200-tonne class face excavators to load 140-tonne capacity dump trucks for waste mining, and 200-tonne class excavators to load 140-tonne capacity dump trucks for ore mining.

Processing Operations

Ore will be processed via a 5.0 Mtpa processing plant. Over the life of mine, the plant will be fed with approximately 89% fresh ore and 11% oxide and transitional ore.

Two-stage crushing followed by a high-pressure grinding roll and a ball milling circuit is planned. A primary gyratory crusher will crush ore to a coarse crush size, followed by dual secondary cone crushers. This will feed a crushed ore stockpile that feeds into a high-pressure grinding roll circuit. Ore will then be passed through a conventional ball mill and milled to 80% passing 106µm (microns).

The milled ore will pass through a gravity circuit comprising two Knelson concentrators for separation and recovery of coarse free gold, to produce a gravity concentrate for cyanidation and electrowinning that can be smelted to produce gold doré. High gravity recovery of approximately 60% is estimated for fresh and oxide/transitional ores at Assafou.

The remaining milled gravity tail will be screened and passed to a carbon-in-leach ("CIL”) circuit containing one pre-leach tank and six CIL tanks in series for leaching and absorption. Leach residence time will be approximately 36 hours.

Following leaching and absorption, gold will be recovered from activated carbon by elution, electrowinning, and gold smelting to produce gold doré.

Extensive and representative metallurgical testwork has indicated that gold is free milling with very high gravity and leach extraction potential, with a projected gold recovery rate of 94% over the life of mine.

Operating Cost Summary

Mining operating cost estimates, prepared by Endeavour, are based on a contractor mining model. Process operating cost estimates were prepared by Lycopodium, who have successfully supported Endeavour through five engineering and construction projects in West Africa over the last ten years. General and Administration ("G&A”) cost estimates were also prepared by Lycopodium with input from Endeavour, as summarised in the table below.

Table 6: Assafou Life of Mine Operating Unit Costs (-15/+20%)

Operating costs have been based on a delivered diesel price of $0.92 per litre and are in line with current local pricing. Power will be sourced from the grid supplying 90kV to site via a ring main system providing power from two different sources of transmission to increase reliability, with power costs estimated at $0.16/kWh.

Capital Cost and Infrastructure Summary

The project capital cost estimate was compiled by Lycopodium with input from Knight Piésold on the TSF, water infrastructure, site access roads and airstrip, from Digby Wells on relocation, and from ECG Engineering on the power infrastructure. Endeavour has provided project specific estimates for mine establishment, facilities and owner's costs.

The initial capital cost is summarized in the table below.

Table 7: Assafou Upfront Capital Cost Estimate Summary (-20/+25%)

The Assafou project capital cost estimate assumes a contractor mining model, selected due to the lower upfront capital costs and the additional fleet flexibility that can accommodate the pre-production mining ramp-up. Within the subsequent DFS, a hybrid approach to contract and owner mining may be considered to ensure capital and operating costs are optimised, while the mining ramp-up is de-risked.

The Assafou project benefits from good surrounding infrastructure, including access to the 90kV power supply within 14km of the project, and access to the A1 national road, which will be diverted around the operation and provide access to the operation. An airstrip will be built 3.5km from the permanent accommodation. Resettlement of two villages within close proximity to the project is required and is included in the capital cost estimate.

The tailings storage facility ("TSF”) is expected to be a cross-valley storage facility, utilising the natural topography of the project area, that will be formed by multi-zoned earth fill embankments, with a total footprint area (including the basin area) of approximately 252ha for the stage 1 TSF to 278ha for the final TSF. TSF construction will benefit from the high availability of fresh waste rock from the mining pre-stripping activities. The TSF is designed to a life-of-mine capacity accommodating a total of 73Mt of tailings, with the potential to be expanded to 110Mt. The Stage 1 TSF is designed for 7.5Mt, approximately 18 months storage capacity, and subsequently, downstream raise construction will be used to progressively increase capacity.

The recommendations from the Environmental Social Impact Assessment ("ESIA”) which is underway, will be used to compile an Environmental and Social Management Plan ("ESMP”) which will guide Endeavour's local community engagement as well as ensuring it fulfils its environment obligations, minimising the mine's impacts where possible. The ESMP will be used to monitor and ensure compliance with environmental specifications, monitoring and management measures and will be implemented from site preparation through to decommissioning and closure. 

Figure 3 below highlights the proposed site and infrastructure layout.

Figure 3: Assafou Schematic Site Layout

Ownership, Permitting, Taxes and Royalties

Endeavour acquired the Tanda exploration permit in 2015, subsequently acquiring the Iguela permit, which contains the Assafou project, in 2017. Endeavour will retain full ownership of the Tanda-Iguela permits until the permits are converted into an exploitation permit. Based on the current 2014 Mining Convention, once the exploitation permit is granted, Endeavour will be entitled to an 80% stake in the Assafou project, while SODEMI (the Ivorian state-owned mining company) and the Government of Côte d'Ivoire will each have a 10% stake.

A corporate tax rate of 25% of gross profit has been applied in the PFS. A royalty of 5.0% and a community levy royalty of 0.5% was applied to all sales. Gold royalties in Côte d'Ivoire are based on a sliding scale with the gold price, and vary between 3.0% and 6.0%. A transport and refining charge of $4/oz Au was also applied.

The mining code is currently under review and if the proposed new mining code is passed into law before the Assafou exploration permit is converted into an exploitation permit, then the fiscal terms applicable to the Assafou project are expected to reflect those of the new mining code. If the new mining code is passed into law in its current draft state, it is expected to include an increase in the Governments free-carried interest from 10% to 15%. This would result in Endeavour's potential stake in the Assafou project, once the exploration permit has been converted into an exploitation permit, decreasing from 80% to 75%.

Geology

Mineralisation at the Assafou deposit is both disseminated and hosted in quartz veins within the Tarkwaian Sandstones. The deposit appears to be monometallic containing no potentially penalising elements associated with the gold. Mineralisation starts at surface, extending down to more than 300 metres in depth, and is continuous along strike, along the prominent northwest trending structure that separates the Tarkwaian Sandstones from the mafic Birimian Basement rocks. The deposit comprises a thick main (up to 60 metres) continuous lens, appearing to be dipping at a low angle to the southwest, overlaid by a series of stacked lenses.

High grade mineralisation and the thickest mineralised intercepts are located adjacent to the structural contact between the mafic Birimian Basement rocks and the Tarkwaian Sandstones along the northeast boundary of the Assafou deposit. Mineralisation at Assafou remains open along strike towards the northwest and towards the southeast, as well as at depth, where deep drilling below 250 metres intercepted mineralisation below the existing resource pit shell and within the Birimian Basement rocks below the sedimentary basin.

Assafou Exploration

The Assafou deposit was discovered in late 2021 and the maiden Indicated resource of 14.9Mt at 2.33g/t containing 1.1Moz and an Inferred resource of 32.9Mt at 1.80g/t containing 1.9Moz was defined on 31 October 2022, less than one year after the initial discovery, based on 58,000 metres of drilling.

Subsequently, an updated Indicated resource of 70.9Mt at 1.97g/t containing 4.5Moz and an Inferred resource of 2.9Mt at 1.91g/t containing 0.2Moz was defined on 14 November 2023, based on 183,000 metres of drilling.

Since the 14 November 2023 resource was defined, a further 44,000 metres of drilling has been completed at the Assafou deposit, extending the mineralised trend by over 0.4km or 12%, to 3.7km, and 26,000 metres of drilling has been completed at near-mine targets, within less than 5km of the Assafou deposit.

Mineralisation at Assafou remains open along strike along the 20km long structural corridor extending from Koume Nangare in the northwest to Kongojdan in the southeast, as well as at depth where mineralisation has been identified below the current resource pit shell, and within the basement mafic Birimian volcanic rocks.

During the first nine months of 2024, 67,000 metres of drilling has been completed for a total spend of $13.4 million, consisting of resource expansion and resource infill drilling at the Assafou deposit, resource definition drilling at the Pala Trend 3 target and reconnaissance drilling at other satellite targets in close proximity to Assafou.

Figure 4: Assafou Deposit Map

Figure 5 below highlights that 2024 drilling, that has not been included in the PFS reserves and resources estimate, has identified mineralisation that extends towards the northwest of Assafou, outside of the existing pit shell. Mineralisation starts at surface within the Tarkwaian Sandstones but extends into the Birimian Basement and it remains open, with further drilling planned for FY-2025.

Figure 5: Assafou Cross Section A3600

Figure 6 below highlights the occurrence of high-grade, stacked lenses of mineralisation in the southeast of the Assafou deposit, where additional drilling was completed in 2023 and 2024.

Figure 6: Assafou Cross Section A0533

Figure 7 below highlights that 2024 drilling towards the southeast of the Assafou deposit has identified high-grade mineralisation below the current Assafou pit shell.

Figure 7: Assafou Cross Section A0300

Figure 8 below highlights that drilling completed in 2023 and 2024 towards the southeast of the Assafou deposit, that was not included in the reserves and resources estimate for the PFS, has identified multiple lenses of mineralisation below the current Assafou pit shell, with follow-up drilling planned for 2025.

Figure 8: Assafou Cross Section A0200

Regional Exploration

Regional exploration continues to advance at nine targets within 6km of the Assafou deposit. The regional exploration programme is targeting both Tarkwaian and Birimian style deposits within close proximity to Assafou that could potentially form satellite pits to the Assafou project.

Figure 9 below, highlights some of the high-grade mineralised intercepts identified at these potential satellite targets, of which the Pala trend 3 target is the most advanced, while further delineation drilling will continue at the other high priority Koume Nangare and Pala Trend 1 and 2 targets.

Figure 9: Iguela Regional Map

Figure 10 below highlights the drilling completed at the Pala Trend 3 target in 2024. Pala Trend 3 is located approximately 1km west of the Assafou deposit, within the same sedimentary basin.

Drilling has identified continuous, stacked lenses of shallow mineralisation that are dipping towards the northeast, towards the Assafou deposit. While mineralisation at Assafou is largely hosted within the Tarkwaian Sandstones, at Pala Trend 3 mineralisation is largely hosted within the Birimian greenstone rocks, similar to other Birimian greenstone deposits in the region. The Tanda-Iguela property remains highly prospective for both types of mineralisation.

The exploration programme will continue to advance the Pala Trend 3 target and a maiden resource is expected to be defined in 2025 and incorporated into the DFS.

Figure 10: Pala Trend 3 P1300 

Next Steps

• The DFS is expected to commence immediately and is due to be completed between late 2025 and early 2026
• Updated mineral reserves and resources will be defined during 2025, which will include additional drilling at the Assafou deposits and the Pala Trend 3 satellite target, and will be incorporated into the DFS
• The exploitation permit application process and the ESIA submission are expected to commence in early 2025
• Further exploration is planned during 2025 on the Assafou deposit and on near-mine satellite targets within close proximity to Assafou

All figures are expressed in United States dollars unless otherwise stated.

Assafou Geology

Mineralisation at Assafou is mainly hosted in Tarkwaian Sandstone, at/or immediately in the vicinity of the structural contact with Birimian Basement rocks (mainly mafic rocks). Gold mineralisation occurs both as disseminated occurrences within pervasively altered sandstone and within, or at the edges of, quartz (±carbonate) veins and breccias that crosscut the altered sandstones. Alteration is reflected by an induration (silicification) and by the presence of sulphides (pyrite), disseminated within the matrix and distributed along the sandstone bedding. The more intense the silicification (and presence of pyrite), the more mineralised the sandstones tend to be.

The structural contact likely controlled the initial sandstone deposition (normal fault in extensional regime). It was then reactivated under an SSW-NNE compressive regime at the brittle-ductile transition, associated with strong mylonitisation and alteration (quartz, carbonate, pyrite, ± sericite, ± chlorite) of the Birimian Basement rocks, and to mafic and felsic intrusions as dykes and sills. Gold mineralisation is likely to have occurred during this reversal, in the post-Tarkwaian reactivation event. Mineralising hydrothermal fluids are believed to have preferentially invaded the Tarkwaian Sandstones rather than the Birimian Basement rocks, due to their higher initial porosity, permeability and competency.

Assafou Resource Modelling

The statistical analysis, geological modelling and resource estimation were prepared by a resource team of Endeavour. The Qualified Person as defined by NI 43-101 is Kevin Harris, Vice President of Resources with Endeavour Mining.

The Assafou mineral resource model was developed in Seequent's Leapfrog Geo, Snowden's Supervisor and Geovia's Surpac software. The database used to generate the mineral resources comprised some 868 drill holes, totalling 183,081 metres. The drill hole data was supported by industry-standard quality assurance and quality control systems, with quality control sampling comprising blanks, coarse blanks, certified reference materials, and field and pulp duplicates. Endeavour's resource team has reviewed the QAQC data available and considers the assay data to be suitable for use in the subsequent mineral resource estimate.

Mineralisation domains were modelled with the Vein System tool in Leapfrog Geo using the interval selection for each vein. The gold assays from the drill holes were composited to 1.0 metre intervals. Grade capping values were applied depending on the mineralised domain, between no cap and 45 g/t. Spatial analysis of the gold distribution within the mineralised zone indicated good continuity of the grades along strike and down dip within the mineralised zones. Variography has been applied using Snowden's Supervisor for the largest mineralised zones (101, 102, 103, 104, 105, 106, 110 and 112) and variogram models were produced for these domains. These largest domains represent almost half of the entire population and have a good geological and grade continuity.

Density measurements from 401 drill holes and covering each of the lithologies, were averaged based on the material type (and lithology, in the case of fresh material). Average density values were applied to the associated portions of the block model as outlined below:

• Laterite 1.79 g/cm³
• Saprolite: 1.96 g/cm³
• Saprock: 2.36 g/cm³
• Fresh: 2.76 g/cm³

The grade estimation was validated with visual and statistical analysis, and comparison with the drilling data on sections with swath plots comparing the block grades with the composites.

The majority of the resource is within the fresh rock, approximately 0.5% of the ounces is oxide, 5.7% is transition and 93.8% is fresh rock.

Endeavour considers that the quality and spatial distribution of the data used, the geological continuity of the mineralisatio