Gold mineralization within the Rosebel deposit is structurally controlled and exhibits similar geological, structural, and metallogenic characteristics to orogenic greenstonehosted gold deposits. Mineralization over the Rosebel property consists of quartz-carbonate tension and shear vein association. Rosebel hosts seven main deposits and several smaller gold occurrences in three mineralized domains.

The North domain is formed by two sub-parallel mineralized trends striking WNW-ESE: the southern trend comprises the PC and EPC deposits (and ETR exploration area), while the northern trend includes the KHJZ deposits (and MK exploration area). The mineralized trends are found on both flanks of an anticline exposing the volcanic rock and plunging 35° to the WNW. The volcanic rocks are overlain by the Rosebel Formation to the south, and by the Armina Formation to the North. A regional dextral strike-slip fault exhibiting late normal movement marks the southern limit of the North domain and is closely associated with the mineralization.

The South domain includes the MA, RM, and RH deposits. The local geology is characterized by the presence of a volcanic basement overlain by detrital sedimentary rocks of the Rosebel Formation. The MA, RM, and RH deposits are all hosted in the footwall of a major reverse fault striking E-W and which is closely related to the onset of mineralization. The sequence is folded into relatively open and slightly dipping (0 to 15°) east or west folds. Mineralization is associated with the major and/or subsidiary shear zones and in the hinges of anticlines.

The RB deposit is hosted in a sedimentary sequence of siltstone and arenite of the Rosebel Formation. RB is the only deposit not located along a volcano-sedimentary contact. The southern portion of the RB pit exposes one interval of conglomerate interbedded within a coarse grained, quartz rich arenite. This sequence evolves to finer grained arenites and siltstones suggesting a general northward younging direction. The sequence strikes 100° and is sub-vertical to steeply dipping to the north. The sedimentary sequence and the mineralization are intruded by three post-mineralization, sub-vertical, north-south diabase dykes.

Mineralization
Three mineralized/structural domains are observed at Rosebel: the North, Central, and South domains. The North domain includes the KH-JZ and PC deposits located along two trends following a WNW-ESE orientation. The Central domain includes the RB deposit, which strikes EW. The South domain is also E-W striking and hosts the MA, Roma (RM), and RH deposits.

Mineralization within the Rosebel deposits is structurally controlled and gold is hosted in both shear and tension veins which are tightly associated in space and time. Relations between veining and folding demonstrate that veining occurred after folding and has commonly borrowed pre-existent structures, such as extensional fractures, or along rock heterogeneities. As a result, elements such as an anticline hinges, lithological contacts and conglomeritic beds have provided structural traps for mineralized fluids. As the veins exhibit no significant signs of deformation, the mineralization is interpreted as being emplaced during the latest stage of the Transamazonian orogeny event.

The general vein mineralogy consists of a quartz - carbonate – tourmaline – plagioclase – pyrite/pyrrhotite assemblage. However, the proportion of the main minerals and the nature of the secondary and trace minerals vary between the different domains. In the South domain, the characteristic vein mineralogical assemblage is quartz + carbonate (calcite) + tourmaline ± chlorite ± sericite ± pyrrhotite ± pyrite, where accessory minerals comprise sphalerite, plagioclase, and magnetite. Alteration aureoles are defined by the presence of chlorite, carbonate (mostly calcite), sericite, pyrrhotite and locally tourmaline and pyrite. In the North domain, the vein mineralogy consists of in an assemblage of quartz + carbonate (calcite – ankerite) + plagioclase + hematite + chlorite ± sericite ± pyrite ± tourmaline. A zonation of vein mineralogy occurs at the deposit scale, with plagioclase and hematite constrained to the main shear zone, while all other minerals are distributed throughout the Rosebel deposits. In the Central domain, the characteristic vein mineralogical assemblage is quartz + carbonate (calcite + ankerite) ± chlorite ± sericite ± pyrite. Ankerite alteration halo is typical of the Central domain and is associated to the highest grade zones.

The Rosebel operation is conventional truck and shovel, drill and blast, open pit operations. RGM runs an owner operated fleet with subcontractors used as support for auxiliary activities.

The Rosebel drilling fleet consists of a mixed fleet of fifteen drills. Drill and blast parameters vary for each of the pits due to different material types and pit designs. All drill holes are 165 millimetres diameter. All blasting activities onsite are executed by Rosebel Gold Mines (RGM) employees. Holes are loaded with bulk explosive matrix and initiated with non-electric detonators.

Ore movement during blasting is a critical issue for the Gross Rosebe operation. For this reason, blast movement monitors are systematically used when blasting mineralized areas to measure vertical and horizontal displacement which allows for the adjustment of the post-blast ore packets. Blast movement is typically in the order of six metres horizontally and approximately three metres vertically on a nine metre bench, according to current measurements.

In order to improve the definition of the ore zones, the preferred method for grade control is through RC drilling in all pits. RC grade control drilling is planned on a grid spacing pattern of 12 metres x 6 metres using inclined holes. Blast hole sampling is used for grade control in areas where RC grade control drilling is not completed. A fleet of four Shram Buggy rigs is used for RC drilling managed by Major Drilling.

CRUSHING, STOCKPILING AND RECLAIM
Run-of-mine from the hard rock stockpile is delivered to the primary crushing facility by haul trucks and front-end loaders. Ore delivery from the mine is on a 24 hour per day schedule. The primary crusher incorporates a 1.37 m x 1.88 m gyratory crusher, followed by a vibrating grizzly and a 2.1 m secondary crushing system that produces the required feed for SAG mill. The crushing product sizing is set at minus 63 mm (2.5”). An active hard rock stockpile is maintained at approximately 50,000 tonnes.

Soft rock feed is maintained through two grizzlies using one dozer and two backhoes, with an active stockpile maintained at approximately 200,000 tonnes. Hard rock/soft rock blending to the SAG feed conveyor is maintained by two 1.8 m x 6.9 m apron feeders respectively.

GRINDING AND CLASSIFICATION
The existing two stage grinding circuit produces a cyclone overflow of P80 74 µm. The product size is expected to increase over time as hard rock content in the feed increases to approximately 100 µm without significantly impacting gold recovery.

The first stage of grinding includes a 9.1 m x 4.0 m SAG mill driven by a 7,500 hp variable speed motor controlled by a Power Flex drive. The SAG mill is operating in an open circuit feeding two 2.4 m x 4.8 m vibratory screens. Screen oversize is processed through a cone crusher with the product returning to the SAG mill feed. SAG mill discharge screen undersize is pumped to the pressure distributor where it is combined with the ball mill discharge and process water.

The second stage of grinding consists of two 5.0 m x 8.2 m ball mills driven by 4,500 hp motors and one 5.0 m x 9.3 m ball mill driven by a 5,200 hp fixed speed motor that operates in a parallel closed circuit. The ball mills operate in closed circuit cyclones. The cyclone underflow reports back to the ball mills for further grinding, while the cyclone overflow, at 35 wt% solids and P80 75 µm to 100 µm flows by gravity to the four 25 m2 linear screens to remove trash from the slurry.

The Rosebel Plant was designed to treat 12.5 Mtpa ore via a conventional cyanidation process. ROM material is processed using a conventional gyratory crusher with a secondary crusher in open circuit and a SAG-Ball milling comminution circuit followed by gravity, CIL process, and associated gold recovery and carbon handling circuits to produce doré.

In 2021, a new plant throughput model was developed to estimate the processing rate as the ratio of hard rock in the Rosebel Plant feed increases.

PLANT
GRAVITY CIRCUIT
Approximately 20% of the cyclone underflow from each cyclone cluster reports to the Sizetec 2.1 m x 4.9 m vibratory screens fitted with 10 mesh panels. Oversize reports to the ball mill discharge pump boxes, and undersize reports to the gravity circuit via a magnetic drum separator at a rate 400 tph. The plant has a gravity circuit consisting of three Falcon concentrators, a Consep Acacia intensive leach reactor, and a Deister table. The conce ........