The Houndé greenstone belt consists of NNE-SSW oriented volcano-sedimentary rocks that are roughly 330 km long by 60 km wide.

The Houndé greenstone belt is made up of andesites, subordinate amphibolitized basalts with intercalations of minor acidic volcanic, gabbroic bodies, greywacke to argillaceous sediments and banded chert. All these rocks are intruded by plutonic bodies consisting of granodiorite, tonalite and quartz diorite batholiths, then by granitic, granodioritic and tonalitic stocks and some small leucogranite intrusions.

The Vindaloo zones are hosted by intensely sericite- and silica-altered mafic intrusions and similarly-altered, strongly foliated and altered intermediate to mafic volcaniclastics and occasionally sediments. The mineralization is often quartz stockwork-style and is weakly to moderately pyritic. The Vindaloo trend has been drill tested for a distance of approximately 7.7 kilometres along strike and up to 350 metres depth. The intrusion-hosted zones range up to 70 metres in true thickness and average close to 20 metres true thickness along a 1.2 km section of the zone called Vindaloo Main. Volcanic- and sediment-hosted zones are generally less than 5 m wide. The entire mineralized package strikes north northeast and dips steeply to the west to vertical. The mineralization remains open both along strike and to depth.

The Vindaloo deposit open pit resources comprise a group of closely-spaced gold mineralized structures that currently represent an approximate 4.8 km section of the Vindaloo Zone and a 0.9 km long section of the Madras NW zone.

The Vindaloo and Madras zones are predominantly hosted by altered magnetite-bearing gabbro and to a lesser extent andesitic volcanic rocks and sediments. The gabbro-hosted zones range up to 70 metres in true thickness and average close to 20 metres true thickness in a section of the zone called Vindaloo Main. Volcanic- and sediment-hosted zones are generally less than 5 m wide.

The mineralized system is zoned with initial propylitic-style alteration along the outer edges of the system with the addition of chlorite and calcite stringers concurrent with the destruction of pyroxene, amphibole and plagioclase. In a poorly defined area, located to the west of the Vindaloo Main zone, the propyltic alteration is overprinted by a reddish hematitic alteration comprising disseminated hematite and hematite veinlets. As the mineralized zones are approached propylitic alteration gives way to increasingly intense, yellowish-colored, sericite-epidote-ankerite+ fucshite alteration of the fragmental andesites. In the strongly altered sections, especially near the gabbro contacts, the fragments are flattened with stretching ratios to 20:1. Occasional quartz-veined zones, with associated trace to 5% finely disseminated to locally crystalline pyrite, occurs in the altered andesites, especially in the hanging wall to the Vindaloo Main zone and in areas along strike of the gabbro-hosted zones where the gabbro is absent. These quartz veins are generally oriented parallel to foliation and shearing.

The gabbro units display a similar alteration pattern as the andesite units with widespread propyltic alteration of ferro-magnesium minerals to complete destruction of the ferro magnesium minerals at the expense of a medium grey mixture of sericite, ankeritic carbonate and quartz. Locally the sericite-carbonate alteration gives way to stockwork-type quartz veining with local silica-enriched rims to the quartz veins and selective silica replacement of feldspar grains, with a focus near unit contacts. At least three directions of quartz veins have been noted. Fine grained to mm-size pyrite crystals are associated with; trace to 10%, up to 2 cm wide, quartz veins (trace to 2% overall in mineralized zones); pyrite-enriched haloes to the quartz veins and; occasionally as disseminations within the host gabbro. Locally fine pyrite crystals are aligned to form poorly defined veinlets. Generally, disseminated sulphide mineralization, returns low gold grades; however, in the Vindaloo NE area, good gold grades are associated with both pyritic quartz veined areas and in areas with disseminated pyrite.

Quartz+-albite+-carbonate+-pyrite veins, associated with the Vindaloo and Madras zones, range from 0.5 to 2 cm thick with the rare vein to a metre wide. During the period from 2011 to 2013 oriented core quartz vein data and other structural data was collected to support interpretation of the geology and mineralized zones. This data indicates that there are three main vein trends in the Vindaloo Main zone area, in order of importance, trending at 030 to 045 degrees, 060 to 070 degrees and 130 to 149 degrees. Veins that trend these three dominant directions vary significantly in dip, supporting the interpretation that most of the veining is stockwork-type in character.

The gold deposits in West Africa have been classified into the following types:

1. Structurally-controlled, epigenetic lode or stockwork mineralization related to major shear zones with native gold (Poura, Burkina Faso; Kalana, Mali),

2. Structurally-controlled, epigenetic lode or stockwork mineralization related to major shear zones and characterized by the inclusion of gold in the crystal structure of the sulphides, often locked in arsenopyrite (Ashanti type: Obuasi, Ghana),

3. Stratiform deposits hosted in tourmalinized turbidites (Gara Deposit Loulo, Mali),

4. Disseminated sulphides hosted in volcanic or plutonic rocks (Syama, Mali; Yaouré, Ivory Coast; granitoid-hosted, Ayanfuri, Ghana),

5. Paleo-placer deposits: auriferous quartz-pebble conglomerates (Tarkwa, Ghana); modern placers (eluvial, alluvial).

The classic structurally-controlled or shear-hosted quartz, sericite schist gold mineralization model with alteration halo (Type 1) matches that of the Vindaloo and Madras NW deposits.

The PEA demonstrated that the Vindaloo and Madras deposits are suitable to conventional open pit mining methods adopting drilling, blasting, trucks and shovels in order to supply ore to a 3 Mtpa treatment plant.

This study has adopted 5 m high benches in ore and 10 m high benches in bulk waste in order to avoid, as much as practical, ore loss and dilution during the mining process.

Blasting will be undertaken utilising industry standard storage, transport and charging practices for a modern mining operation, subject to all local and national statutory and regulatory requirements.

The Run of Mine (ROM) pad will be used to provide a buffer between the mine and the plant. The ROM stockpile will allow blending of ore feed stocks, and will ensure a consistent feed type and feed rate to the plant. ROM ore will be loaded into the crushing circuit feed bin (ROM bin) by direct tipping from the mining haul trucks or by front end loader (FEL).

ROM ore will be drawn from the ROM bin at a controlled rate by an apron feeder and discharged onto a vibrating grizzly. The grizzly oversize will report to the jaw crusher for primary crushing. The jaw crusher product together with grizzly undersize will report to the primary crusher discharge conveyor feeding directly to the crushed ore stockpile.

Ore will be withdrawn from the coarse ore stockpile and fed via the mill feed conveyor to the SAG mill. Lime and SAG mill grinding media will be added to the mill feed conveyor as required.

Milled and screened slurry will report to the gravity circuit where it will be treated by centrifugal gravity concentrators to recover the free coarse gold and gold associated with coarse sulphide and silicate particles. The low mass gravity concentrate (2 to 3% of feed tonnage) will report to the concentrate UFG circuit and the gravity tails will report to pre-leach thickening.

The gravity concentrate treatment circuit will consist of a UFG mill in closed circuit with hydrocyclones and a concentrate leach circuit.

The gravity concentrate will gravitate to the concentrate storage tank which will provide a buffer for the UFG circuit. Provision will be made to add peroxide solution to the concentrate storage tank. UFG feed slurry will be pumped to the UFG mill for fine grinding. The ground slurry will be diluted and pumped to the UFG cyclones for classification. The UFG cyclone underflow (material requiring further grinding) will report to the concentrate storage tank for further grinding. The UFG cyclone overflow (reground concentrate size material) will gravitate to the concentrate leach tanks.

The concentrate leach circuit will consist of two leach tanks providing 4 hours residence time. Caustic and peroxide solutions will be added to ensure that the slurry pH (caustic) and dissolved oxygen level (peroxide) is suitable for cyanidation. Sodium cyanide solution will be metered into the leach circuit and air from dedicated blowers will be sparged down the shafts of the leach agitators to provide oxygen to the leach slurry.

Leached concentrate will be pumped to the CIL circuit for gold adsorption as well as using any residual sodium cyanide in the concentrate slurry.

Tails from the gravity circuit will be thickened in a high rate thickener prior to CIL. The thickener feed slurry will be mixed with flocculant and will report to the pre leach thickener.

The thickened slurry (thickener underflow) will be pumped to CIL and the thickener overflow will gravitate to the adjacent mill water tank and will be distributed as dilution water to the milling and UFG circuits. Process water from the process water pond will be added to the mill water tank to balance mill water\ requirements.

The adsorption circuit will consist of six CIL adsorption tanks providing 36 hours residence time (the minimum 24 hours required by the testwork can still be achieved if the thickener is by-passed). The tanks will be interconnected with launders and slurry will flow by gravity through the tank train.

Pre-leach thickener underflow and leached concentrate will be combined as CIL feed. Quicklime added to the mill feed conveyor will ensure that the slurry pH is suitable for cyanidation and sodium cyanide solution will be metered into the CIL circuit. Air from dedicated blowers will be sparged down the shafts of the CIL agitators to provide oxygen to the leach slurry.

Barren activated carbon will be added to the last tank and advanced counter current to the slurry flow. The leached gold will adsorb onto the carbon and be removed from the CIL slurry. Carbon loaded with gold (loaded carbon) will be recovered from the CIL slurry via the loaded carbon recovery screen and will report to the elution circuit.

Slurry from the last CIL tank (CIL tails) will gravitate via the carbon safety screen to the cyanide destruction circuit.

The following operations will be carried out in the elution and goldroom areas:
- Acid washing of loaded carbon.
- Stripping (elution) of gold from loaded carbon using the split AARL method.
- Electrowinning of gold from pregnant solution.
- Smelting of electrowinning products.
- Regeneration of barren carbon.

Loaded carbon will be washed with a dilute acid solution to remove contaminants prior to being rinsed with water. The loaded carbon will be eluted with a hot dilute cyanide / caustic solution which will recover the gold from the carbon into the solution. The gold solution (pregnant solution) will be pumped through electrowinning cells and the gold will be recovered onto the cell cathodes. The gold will be removed from the cathodes by high pressure water jets with the gold sludge being filtered and dried prior to smelting with fluxes in a furnace to produce doré bars.

Eluted carbon (barren carbon) will be transferred to the carbon regeneration kiln for reactivation prior to re-use in the CIL circuit.