The Mato Bula gold-rich VMS deposit is the main deposit discovered to date within the Adyabo Project, and covers the Mato Bula North, Silica Hill North, Silica Hill, Mato Bula, Jasper Hill and Halima Hill mineralized zones.

Two mineralized structures are present at Mato Bula Hill; the Main lode and the Upper lode.

The Main lode at Mato Bula is located south of the crest of the Mato Bula Hill, and is a narrow high-grade gold shoot extending over a strike length of 120 m at surface. Numerous active artisanal gold bedrock workings are present at Mato Bula exploiting this gold lode, and an upper lode, reportedly to a depth of 46 m.

The shoot has steep dip, vertical plunge, and maximum true width of 3 m. At depth the maximum strike of the shoot is reduced to 80 m, but the structure remains open at depths greater 220 m below surface.

Silica-pyrite alteration is extensive laterally (750 m strike) and in thickness (159 m wide), and zones of silica-pyrite are present in the hanging wall and along strike, in a zone up to 150 m wide and 750 m long.

Mineralization is hosted within a shear zone that contains abundant quartz veining, silicification, sericitization and carbonate alteration. Gold is associated with chalcopyrite-rich veins in intense silica alteration, and also the presence of possibly V-rich mica (roscoelite). The Main lode averages 5.5 g/t gold and 0.61% copper, and has a high gold:silver ratio of 10.2. Lead and zinc concentrations are negligible.

The Jasper Hill zone (sometimes known as Mato Bula South) contains structurally controlled gold lodes (vein/wall rock porphyry hosted), and extend from the Mato Bula zone in the north towards Halima Hill in the south. The upper and main lodes within this zone exhibit more complex geometry due to possible faulting (or slumping) and wall rock interaction. Mineralization is lithologically controlled with the gold-bearing zones within a jasperoid alteration zone. Gold concentration decreases, with increasing zinc concentration, moving away from the jasperoid unit. Gold-bearing veins have also been identified perpendicular to the long core axis.

The Main lode at Jasper Hill is located 40 m southeast of the Upper lode, southwestwards along strike from the Mato Bula zone, and outcrops along strike for 80 m. The structure has a maximum true thickness of 9 m, and an average gold grade of 4.53 g/t and copper grade of 0.85%. It has the highest gold:silver ratio in the Mato Bula prospect of 5.3:1, and a low gold:copper (x10) ratio of 0.56:1. The average silver concentration is low, 0.85 g/t, and only trace amounts of lead and zinc are present. The lode plunges at approximately 60 to 70° to the southwest, and remains open down plunge below depths of 200 m from surface.

The most southerly manifestation of the Mato Bula Trend is the mineralized zone at Halima Hill, 320 m to the southwest of the Jasper Hill zone. Halima Hill was targeted due to the presence of artisanal trenching, with lower order gold-copper geochemistry present within an alteration zone. Apart from a zone of subcrop at Halima Hill, much of the southern part of the trend is covered in thick (50 cm to 2 m) transported colluvium, thus reducing the geochemical signature at Halima Hill relative to the hilltop workings of Mato Bula North, Silica Hill and Mato Bula.

Mineralization was present as pyrite- chalcopyrite bearing quartzveins within altered tuffs. The assay results and visual interpretation of alteration at Halima Hill indicate the Mato Bula system is weakening to the south near surface, however the IP survey is suggestive of additional increasing potential at depth.

Open pit mining is planned as conventional truck and shovel open pit mining with drill and blast.

The PEA open pit contains the following:
• 3.3 Mt of potential mill feed
• 30 Mt of waste rock (including mineralized material below cut-off grade)
• 322,000 tr oz of gold
• 75,000 tr oz of silver
• average NSR US$111/t processed.

The pit consists of three distinct sections, namely a northern satellite pit with high grades, a central pit from which much of the mill feed will be sourced and a southern limb which mines shallow mineralisation with lower grade.

The pit slope design is based on a maximum overall slope of 49°. The bench heights for mining are designed at 5 m high, with triple benching between catch benches of 5 m wide. Haul roads are designed around the width of 25 t articulated dump trucks and are planned as 15 m wide.

Mining will be managed by qualified engineering professionals such that the operations are conducted safely and efficiently. The management of operations will include mine planning, surveying of open pits, assaying of rock to be mined for minerals, and geotechnical engineering for pit walls and WRSF stability.

Mining will be done by first drilling and blasting the rock so that it can be loaded by loader onto haul trucks. Waste rock will be transported by haul trucks to designated WRSF, while rock containing mineralization will be transported to the crusher for subsequent processing.

Drilling and blasting has been considered for the PEA. It is assumed to consist of drilling of 5 to 10 m bench heights with 89 and 115 mm holes. Tetra Tech has made provisions for track mounted drill rigs for drilling blast holes.

The holes would be charged primarily with ammonium nitrate and fuel oil (ANFO) where possible and cartridged emulsion explosive if holes are wet. Initiation is assumed to be carried out using nonel systems with pentolite boosters. Explosives will be stored onsite, with blasting carried out at the end of shifts to ensure minimal disruption to other pit activities.

For this PEA, loading was assumed to be done by excavator with support from a wheeled loader. The minimum mining width has been included in the design as 15 m based on selected equipment operating widths.

The Mato Bula processing facilities is designed to process a nominal 500,000 t/a, or 1,400 t/d, of gold-copper-bearing material from an open pit mining operation. The concentrator is designed to produce a copper concentrate containing a high level of gold and a gold concentrate produced by gravity concentration that can be sold directly. A gold-bearing by- product of the flotation process contains a sufficient level gold that will be treated using agitated cyanide leaching to maximize gold recovery. This material is planned to be treated off site at the nearby Da Tambuk process plant, which is proposed for development, or other facilities.

The conventional crushing and ball mill grinding in closed circuit with hydrocyclones are proposed for comminution. A centrifugal gravity concentrator has been incorporated in the grinding circuit to recover coarse and liberated gold particles, and a shaking table will be used to upgrade the gravity concentrate. The ball mill cyclone overflow will be treated in a conventional flotation circuit to produce a gold-bearing copper concentrate and a gold-bearing pyrite product for further cyanidation treatment to recover gold.

The rougher flotation copper-gold concentrate will be reground by a regrind ball mill to improve copper and gold mineral liberation. The copper-gold bulk flotation tailings will be further floated to produce a gold-bearing pyrite concentrate. The discharge of the regrind ball mill circuit in closed circuit with a cyclone will report to the cleaner flotation circuit for upgrading to produce a final copper gold concentrate. The cleaner flotation circuit consists of three stages of cleaning. The cleaner scavenger concentrate will report to the rougher concentrate regrinding circuit. The cleaner scavenger flotation tailings carrying some gold will be directed to the gold-bearing pyrite dewatering circuit where the pyrite concentrate will report.

The final concentrate from the third cleaner flotation will be pumped to the concentrate thickener for dewatering with the decant solution recycled to the process. Concentrate thickener underflow will be pumped to a final concentrate holding tank and then to a pressure filter for further dewatering. The filter cake will be conveyed to a concentrate storage shed prior to being transported offsite. The haul trucks will be equipped with dust covers to prevent concentrate dust from escaping during transport. The concentrate will be hauled to the designated seaport for ocean shipment to offshore copper smelters.

The gold-bearing pyrite flotation concentrate, together with the copper cleaner scavenger concentrate, will be sent to a gold-bearing pyrite concentrate thickener for dewatering, and the pyrite thickener underflow will be further dewatered by a plate and frame type pressure filter. The dewatered pyrite concentrate will be transported to the nearby Da Tambuk cyanide leaching plant or other facilities for additional gold recovery.

The pyrite flotation circuit tailings are the final tailings and will be pumped to the tailings thickener. The tailings thickener underflow will be pumped to the TCF while the thickener overflow will be reused as process water.

Both the cleaner scavenger flotation tailings and the pyrite flotation concentrate will be dewatered. The blended gold-bearing material will then be transported to the nearby planned Da Tambuk cyanidation process plant or other facilities for gold recovery.

The overflows of the concentrate, pyrite and tailings thickeners and the recovered water from the TCF will be reused as the process water. Fresh water will be used for gland services, reagent preparation and gravity circuit fluidization, as well as for process water make-up purposes, as required.

The Mato Bula processing facility will consist of the following unit operations:
• two-stage crushing with the second stage in closed circuit with a screen
• crushed material bin storage and reclaim
• ball mill grinding in closed circuit with cyclone
• gravity recovery circuit
• copper-gold bulk rougher flotation circuit
• regrind ball mill in closed circuit with cyclone
• three stages of cleaner flotation circuit
• concentrate dewatering circuit, including a thickener and a pressure filter
• concentrate storage and loadout
• gold-bearing pyrite flotation circuit
• gold-bearing material dewatering and loadout
• tailings thickening
• TCF
• process water and fresh water supply systems.