Essakane is situated in the Paleoproterozoic Oudalan-Gorouol greenstone belt in northeast Burkina Faso. The local stratigraphy can be subdivided into a succession of lower-greenschist facies meta- sediments (argillites, arenites and volcaniclastics), conglomerate and subordinate felsic volcanics, and an overlying Tarkwaian-like succession comprised of siliciclastic meta-sediments and conglomerate. Each succession contains intercalated mafic intrusive units that collectively comprise up to 40% of the total stratigraphic section.

The region preserves evidence for at least two regional deformational events. D1 structural elements such as the Essakane host anticline are refolded by a series of North-Northeast-trending F2 folds. Later localized deformation occurs near the margin of a calc-alkaline batholith in the south of Essakane. The Markoye fault trends North-Northeast through the western portion of Essakane and separates the Paleoproterozoic rocks from an older granite-gneiss terrane to the west.

The Korizéna prospect is situated approximately 10 kilometres west of the Essakane deposit and is the southern continuity of the Gossey deposit. Both have similar geology.

The geology of the Gossey deposit includes sequences of detrital sedimentary rocks (quartz-arenites, quartz- feldspathic sandstones, fine to microconglomeratic lithic sandstones with polygenic clasts, lithic sandstones with pelitic fragments, greywackes, argillites/ graphitic siltstones) interbedded with igneous rocks (gabbro, diorite, gabbro-diorite, andesite) mainly arranged as sills and dykes (Allou et al. 2013). Structurally, this prospect is controlled by the Markoye fault especially its branch named the Gossey- Korizéna shear zone. The Markoye fault is a regional structure close to the prospect characterized by a predominantly NNE-SSW reverse directional sinistral shear corridor. The main deformation structures observed on this corridor are schistosity and shear planes. The effect of weathering makes it very difficult to measure these in the field. These measurements were mainly carried out on the oriented core and confirmed that the schistosity planes were parallel to the stratification. A more detailed analysis of these planes (stratification and schistosity) by zone reveals a progressive flexure of the orientations, going from the NNE-SSW with dipping an average 60° east in the north, towards the NE-SW with a dip subvertical and slightly inclined westwards to the south (Allou et al. 2013). In addition to this schistosity, other structures are observed: asymmetrical sheared quartz veins (boudins), tension veins arranged in echelon and sigmoid clasts. This corridor is also marked by quartz veins of decametric size and oriented from N10° to N40°. Sometimes these veins are parallel to the shear corridor and have a brecciated structure characterized by crushed quartz taken from siliceous cement.

Mineralization
The EMZ deposit is an orogenic gold deposit characterized by quartz-carbonate stockwork vein arrays and is hosted by folded turbidite succession of arenite and argillite. Gold occurs as free particles within the veins and is also intergrown with arsenopyrite +/- tourmaline on vein margins or in the host rocks. The gold particles occur without sulphides in the weathered saprolite. The gold is free-milling in all associations. The vein arrays are complex and consist of: (i) early bedding parallel laminated quartz veins, (ii) late steep extensional quartz veins, and (iii) pressure solution cleavage (with pressure solution seams normal and parallel to bedding).

Alteration in the host arenite unit typically consists of a sericite > carbonate > silica ± albite ± arsenopyrite ± pyrite assemblage. Arsenopyrite and pyrite occur within and adjacent to quartz veins or are disseminated throughout areas of wall rock alteration. Traces of chalcopyrite, pyrrhotite, galena and hematite can occur with the arsenopyrite. Gold occurs as free particles within the veins and also as intergrowths in arsenopyrite on vein margins or in the host rocks.

The Gossey deposit mineralization is mainly hosted in sandstone to conglomeratic sedimentary formations along contacts with basic to intermediate intrusive dykes, and rarely within these intrusive units. Gold mineralization is also associated with quartz-vein (brecciated, banded, sheared, and as boudins) systems present in highly silicified zones and accompanied by sulphides.

At the Wafaka deposit, gold mineralization appears to be controlled by a series of shear zones and occurs in a network of parallel fracture systems associated with calcite and quartz within strongly deformed and hydrothermally altered turbidite rocks. The contact between the sedimentary sequences and the dioritic intrusion (dykes and sills) sometimes contains gold.

Drill cutting and core observations have confirmed that the gold mineralization in the Falagountou West deposit is structurally controlled, hosted in sheared and brecciated zones in the hanging wall contacts between sedimentary and intrusive rocks along a north-northwest to north trend. Gold is associated with quartz veins and is found disseminated in the wall rock as well. There is a strong spatial relationship between the gold mineralization structures and the swarm of intrusive dykes that intrude the sedimentary sequence, suggesting that part of the fluid responsible for the gold deposition may have been exsolved from the dioritic magma during its emplacement. The alteration assemblage encountered is silica-calcite- chlorite. Pyrite and arsenopyrite are the main sulphide minerals observed to date, both in sedimentary rocks and in the dioritic dykes.

The Lao deposit is the southern extension of EMZ. The geological setting of this deposit is almost similar to EMZ. It is composed of alternating sequence of argillite and arenite intercalated by intermediate to mafic sills and crossed by some late dolerites dykes. The main structure seems to be a North-East dipping recumbent fold. The gold mineralization is associated with zones of complex networks of fractures systems filled by quartz and quartz-carbonate. The hydrothermal alteration is composed of silica, carbonate and sometime chlorite and epidote. Also pyrite is observed associated to gold.

Mining is carried out using a conventional drill, blast, load, and haul surface mining method with an owner fleet. Approximately 12.95 Mt of ore at an average grade of 1.31 g/t Au for a total of 457,286 oz of gold were produced in 2021. Currently the mining plans are limited to the Essakane main pit and its Gorouol satellite pit.

The Falagountou, Wafaka, EMZ North satellite pits that provided additional ore and operational flexibility are currently mined out. The North satellite pit is currently being used as a reservoir while the Wafaka and Falagountou pits are currently undergoing final closure studies.

Various ore stockpiles, sorted per type (saprolite, transition, or fresh rock) and grade (marginal, low, and high grade), are located to the west of the main pit, just north of the primary crusher.

The ore is crushed in a gyratory crusher and in a cone crusher. The crushed ore is stockpiled either in a pile for Line A or Line B. The ore is reclaimed with apron feeders and feeds SAG mills on each line. The pebbles from the SAG mills are diverted to their respective pebble crusher in closed circuit. The ore passing through the SAG mill discharge screen feeds a pack of cyclones. Cyclone underflow returns to the ball mill. Cyclone overflow is sent to the preleach thickener. A portion of cyclone underflow goes to the gravity concentrators (two on each line).

Ore is currently processed using two stages of crushing, SAG, ball mill grinding, pebble crusher grinding (SABC), gravity concentration, and a CIL gold plant. The 2008 updated financial statements proposed a process plant throughput rate of 7.5 Mtpa. During construction, some debottlenecking improvements were made to the design, resulting in a revised nameplate capacity of 9.0 Mtpa based on processing 100% saprolite ore. Due to further operational improvements, plant throughput has increased beyond the constructed design capacity.

Fresh rock CIL plant feed has gradually increased from 2012 onwards. To maintain gold production levels, with increasing proportions of fresh rock in the CIL plant feed, an expansion was completed in 2014. The objective was to double the fresh rock processing capacity from 5.4 Mtpa on a 100% fresh rock basis to 10.8 Mtpa.

The CIL plant expansion was commissioned in February 2014, and effectively doubled the fresh rock processing capacity ........