Gold deposits in the West African metallogenic district, including those on the Sabodala Project and the company's adjacent exploration concessions, show many characteristics consistent with their classification as orogenic (mesothermal) gold deposits and prospects. In addition to the deposits in western Africa, these include some of the largest gold deposits globally of variable age, such as the Archean aged Hollinger and Red Lake deposits in Canada and Kalgoorlie in Australia. Orogenic gold systems are structurally controlled deposits formed during regional deformation (orogenic) events. The term orogenic refers to deposits sharing common origin in metamorphic belts that have undergone regional compressional to transpressional deformation (orogenesis), often in response to terrane accretion or continent-continent collisional events.

Orogenic gold deposits exhibit a range of styles dependent on metamorphic grade, setting, fluid type, and fluid/confining pressure. They often include spatially associated quartz shear veins, extension vein arrays, shear zone and disseminated sulphide styles. At greenschist grade, vein dominated styles such as those developed in the Sabodala district contain quartz-carbonate ± albite ± K-feldspar veins with up to 10% (pyrite ± arsenopyrite ± base metals) sulphides and associated Fe-carbonate albite, chlorite, scheelite, fuchsite and tourmaline as associated vein and hydrothermal alteration assemblages. Vein systems and shear zones are often semi-brittle in style, including both brittle veining styles (extension veins and fault hosted brecciated shear veins), which alternate with periods of ductile deformation, producing sequences of early folded and younger less strained vein systems during latter periods of regional deformation at peak to immediate post-peak metamorphic timing. Sigmoidal extension vein arrays are often present and are typical of the deposit style. This deposit type often also has great vertical extent providing potential for discovery of significant down dip and down plunge continuations of mineralized zones.

Principal structures on the Sabodala Mining Concession form a steeply west-northwest dipping, north-northeast trending shear zone network, which has previously been referred to as the "Sabodala Shear Zone". The north-northeast trending shear zones at Sabodala likely represent first and second order structures of regional scale to first order features such as the MTZ , while the northwest trending shear zones may be third order features that accommodate strain between these higher order features.

Gold mineralization at the Sabodala deposit occurs in a combination of occurrences. Continuous grey quartz shear veins along shear zone surfaces in the Main Flat and Northwest shear zones, in sets of quartz-carbonate-albite-pyrite extension veins, in coalescing extension and shear vein domains forming zones of quartz-carbonate matrix breccia, and in areas of pervasive tan to pink coloured carbonate-albite-sericite-pyrite alteration which surrounds and links between veins, shear zones and breccia. Multiple generations of veins are evident, but the most voluminous veining and alteration forms the youngest generations.

The Niakafiri East deposit consists of the former Niakafiri Main, Dinkokono, and Niakafiri Southeast deposits, which are located adjacent to and along strike from each other. Gold mineralization is located within the north-northeast trending Niakafiri Shear zone that extends across the Niakafiri East area. Gold mineralization comprises sets of quartz veins, shear veins and disseminated pyrite developed in the ultramafic-hosted carbonate altered ductile Niakafiri Shear Zone, steeply dipping to the west. Mineralization is generally concentrated in areas of both most intense strain, and most pervasive dolomite-sericite alteration where networks of quartz extension and shear veins are developed, often spatially associated with fine-grained pink felsic dykes that occur in close proximity to the mineralized shears. The intersection of north-northeast and north-northwest trending shear vein sets and associated fringing sets of steeply dipping, east-west trending extension veins defines steep northerly plunging shoots.

The Goumbati West deposit is located southwest of the Maki Medina and Kobokoto south gold deposits and is an extension of the Niakafiri West Shear. The gold mineralization at Goumbati West occurs within a 1.2 km long north-northeast trending shear structure. Goumbati West is a north-northeast trending gold in quartz vein system comprised of several zones occurring in a sequence of epiclastics and basalt.

Gora is hosted by a moderate to steep southeast dipping, northeast trending sequence of turbiditic sandstone, siltstone, carbonaceous siltstones, and mudstone which is at least locally overturned by tight to isoclinal folding which are consistently down facing towards the west.Veins dip between 45º and 55º to the southeast. Veins vary locally to several metres thick and typically are banded with grey and white quartz.

The Masato deposit is located several kilometres to the north of Golouma West, within a zone of highly magnetic mafic and ultramafic volcanics. The geology of Masato is dominated by a north-northeast-south-southwest (~020º) trending ductile shear zone several tens of metres in width. The shear zone fabric dips approximately 70º west with local areas of intense metre-scale folding. Some ultramafic rocks are affected by the shearing and commonly appear “greasy”, possibly resulting from alteration by talc and serpentine. Carbonate dominated alteration is relatively widespread; however, fuchsite is present in addition to the carbonate-quartzsericite assemblage, particularly within ultramafic units.

The geology of the Golouma area is dominated by moderately deformed massive flows and pillowed basaltic rocks. The rocks are moderately chloritized, which in some instances is accompanied by the development of epidote replacement. Hydrothermal carbonatedominated alteration overprints the rocks where deformed by ductile shear. In areas of low strain, the alteration yields a wispy appearance, but in more highly deformed zones, it imparts a buff or salmon-pink colouration and is associated with anomalous gold concentrations. Several felsic dykes, up to 5 m in width, occur throughout the Golouma area and appear to be intimately associated with the gold mineralization, particularly in Golouma South. A small number of mafic dykes have been recognized in drill core, including one larger gabbroic dyke approximately 12 m in width.

The Kerekounda deposit is located approximately 1.5 km to the north of the Golouma South deposit, within the same east-northeast-west-southwest structural trend that hosts the mineralization of the Golouma area. The deposit is hosted by weakly to moderately deformed mafic volcanics, similar to the host rocks at Golouma. The main ductile foliation orientation is 060-240°, consistent with the east-northeast trending regional structure.

Three distinct shear zones host the mineralization at Kerekounda. Each zone typically ranges from one metre to 10 m width and high-grade shoots plunge steeply toward the westnorthwest. The plunging shoots appear to be controlled by the intersection of the regional north-northeast trending shear zone fabric, which controls the location of mineralization in the Golouma-Kerekounda area, with the discrete north-northwest trending shear zones that host the mineralization. Of the three mineralized shears, it is the eastern most shear which is most prevalent. It comprises a quartz-carbonate vein and multiple veins and/or vein breccias, within a broader zone of carbonate dominated alteration. The highest gold grades occur with the quartz veins especially those containing tourmaline while lower grades are generally found in the adjacent altered rock.

The Sabodala open pit commenced production in March 2009 and has since been in operation.

At the Sabodala-Massawa complex the open pit mining method used is conventional drill and blast, truck and shovel and is conducted with Endeavour’s own fleet. The current fleet includes a total of 70 mobile mining equipment units.

The mine operates using 10-meter blast benches mined in 5-meter flitches for waste and two 2.5-meter flitches for ore. Open pit mining operations assume selective mining with respect to both weathering type, process route and grade categories. The current mining strategy assumes the selective mining of the higher-grade material to enable separate processing of the high-grade fresh refractory and non-refractory components.

All surface ore haulage and supply of explosives is outsourced to a specialist contractor. Grade control drilling is carried out by a combined owner and contractor drilling fleet.

The selected mining method is Cut and Fill for use at the underground deposits at Sabodala. Two deposits will be mined concurrently in order to meet the current mine life schedule, with each deposit scheduled at 500 tpd production, providing approximately 1,000 tpd combined peak underground ore production. Kerekounda and Golouma South will be mined first. Once they are exhausted, the Golouma West deposits will be mined.

The underground mine construction begins in year 2027, with ore production in 2028. The open pit mining ends in year 2034 and the remaining LOM comprises mining from the underground and stockpile reclaim. With additional open pit resources and reserves, it is anticipated that the underground portion will be extended further in the future from the current LOM schedule.

Crushing, Stockpiling and Reclaim The primary crushing circuit will reduce the run of mine (ROM) material from a nominal top of size of 800 mm to a product size of P80 of 150 mm. When handling feed for the WOL plant, rear dump trucks deliver ROM ore to two identical primary crusher facilities operating in parallel. Ore delivery from the mine is on a 24 h/d schedule. Front-end loaders (FEL) feed ROM ore to the ROM bins from where apron feeders transfer material to the vibrating grizzly feeders. Vibrating grizzly feeder oversize feeds the jaw crushers while the undersize material bypasses the jaw crushers. The combined primary crushed ore and vibrating feeder undersize are conveyed to triple deck screens that segregate the material into two particle size distributions. Screen oversize material is conveyed to the coarse ore stockpile (COS). Screen undersize material is conveyed to the secondary crusher feed bin that feeds the secondary crusher. The secondary crushed material is then conveyed to the secondary crushed ore stockpile (SOS). An apron feeder and two vibrating feeders located under each of the two stockpiles reclaim crushed ore to feed the milling circuit. Following the Phase 1 modifications a blend of Sabodala and Massawa free-milling ores are fed into both crushing circuits. No modifications to the crushing circuits are required. In Phase 2, circuit modifications will be required to crush and keep separate the refractory ores coming into the process plant. Modifications include the installation of flop gates, bypass chutes and a conveyor to feed the refractory ore to a new refractory crushed ore stockpile. The crushing circuit daily operation will be divided into two modes of operation, campaign crushing the different ores as follows: For part of the day: Crusher No 2 will be fed refractory material with primary crushed ore fed to the new ROT plant crushed ore stockpile. Simultaneously, Crusher No. 1 will feed free-milling ore to the existing WOL stockpiles. Balance of the day: Both crushers process WOL material. Crushed ore from the refractory crushed ore stockpile is reclaimed by two apron feeders to feed the ROT SAG mill. WOL Grinding and Classification Free-milling ore is ground in the existing WOL SABC grinding circuit in two stages to produce a P80 of 90 µm product to feed the leach circuit. The first stage includes a SAG mill and the second stage includes two ball mills. Ore is conveyed from the COS and SOS to the SAG mill feed chute from where it is mixed with water to form a slurry. Lime is metered onto the SAG mill feed conveyor to control the pH of the slurry feeding the leach circuit. Slurry discharges from the SAG mill through a trommel screen and onto a vibrating screen. Screen oversize is transferred to the pebble crusher from which the crushed material is returned to the SAG mill feed conveyor. Screen undersize gravitates to the primary cyclone feed hopper where it is combined with Ball Mill No. 1 discharge. The two ball mills operate in closed circuit with two cyclone clusters. Cyclone underflows reports back to the ball mills for further size reduction. Cyclone overflows are fed to two parallel trash screens for trash removal.

The existing WOL plant at the Sabodala operation has a design capacity of approximately 4.0-4.2 million tonnes (or an average of over 500 t per operating hour) of a blend of fresh and oxide ore per year and which has been achieved since the last upgrade was completed in 2016. The plant comprises facilities for crushing, grinding, leaching, carbon-in-leach (CIL) cyanidation, acid wash and elution, electrowinning, bullion smelting, carbon regeneration and tailings disposal. Additions and modifications are immediately required to the existing Whole Ore Leach (WOL) plant to prepare it for treating higher grade material from the Massawa pits (Phase 1). A new Refractory Ore Treatment (ROT) plant is required to treat refractory ores commencing in 1Q 2023 (Phase 2). The WOL process plant modifications are designed based on a plant throughput of 4.0 million tonnes of free-milling ore per year, with an average gold head grade of 1.51 g/t, achieving 91.2% gold recovery. In the short term, h ........