Burkina Faso

Bomboré Mine

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Categories

Overview

Mine TypeOpen Pit
Commodities
  • Gold
Mining Method
  • Truck & Shovel / Loader
Production Start... Lock
Mine Life2035
ShapshotOn December 1, 2022, the Bomboré Gold Mine achieved commercial production.

Owners

SourceSource
CompanyInterestOwnership
Government of Burkina Faso 10 % Indirect
Orezone Gold Corp. 90 % Indirect
Orezone Bomboré S.A. (operator) 100 % Direct
The Bomboré Mining Permit is registered in the name of Orezone Bomboré S.A. (OBSA), a 90% owned subsidiary of Orezone Inc. s.a.r.l., itself a 100% owned subsidiary of Orezone Inc., which is 100% owned by Orezone Gold Corp.

Deposit type

  • Hydrothermal
  • Vein / narrow vein
  • Orogenic

Summary:

The Bomboré gold deposit is the principal gold mineralization of potential economic significance found to date on the Property. It is located in an area that is principally prospective for orogenic gold deposits. Similar to gold deposits found elsewhere in late Proterozoic Birimian terrains of West Africa, the Bomboré gold deposit exhibits a structural control and hydrothermal activity. It is a large tonnage, low grade system that has similar characteristics to other Birimian gold deposits such as Kiaka in Burkina Faso, Damang, Yamfo-Selwi and Obuasi in Ghana, and the Sadiola deposit in Mali.

Hydrothermal deposits are typically late orogenic deposits and exhibit strong relationship with regional arrays of major shear zones. The gold mineralization is typically associated with a network of quartz veins containing subordinate amounts of carbonate, tourmaline, sulphides, and native gold. In these deposits, the gold is typically free milling. Alternatively, the gold mineralization can also be associated with disseminated sulphides in strongly deformed alteration zones. In the latter case, gold may be free milling but also locked in the sulphide lattice structure and refractory. The Bomboré deposits are stratabound disseminated sulphide bodies preferentially hosted in the meta-gabbro and meta-argillite lithologies, which are interpreted to have acted as preferential gold traps during a syntectonic deformation and metasomatic event due to their chemical and rheological characteristics.

The Bomboré gold deposit occurs within the regional Bomboré Shear Zone (BSZ), a major north to northeast trending structure considered as a subsidiary to the Tiébélé-Dori-Markoye Fault. Eleven separate auriferous zones have been delineated by drilling within the 14 km segment of the BSZ located within the Property. The gold deposits were discovered by tracing gold-in-soil anomalies to bedrock by drilling.

The gold mineralization in the Property area is associated with arrays of structurally controlled quartz veins and veinlets and attendant silica, sulphide, and carbonate alteration developed within the BSZ. Most quartz veins are oriented sub-parallel to the foliation and exhibit strong strain, however, the presence of relatively unstrained quartz veins and breccia in drill core attest the long protracted history of vein formation and deformation. Late west trending veins crosscutting the main foliation fabric are also observed. Locally, there is evidence suggesting that gold mineralization was remobilized into northeast and southeast dilation zones associated with late faults.

The quartz associated with the gold mineralization is milky white to smoky, locally vitreous and may contain tourmaline. The widths of the veins range from two centimetres to one metre, with an average of ten centimetres. The near surface gold mineralization with grades of up to 0.2 g/t Au is pervasive regardless of quartz veining and is associated with fine disseminated sulphides, predominantly pyrite.

Generally, the gold occurs as fine grain electrum (< 10 µm) but can be visible in outcrop. Artisanal mining over the last 15 years attests to the existence of coarser gold locally. Gold occurs as free gold in quartz veins and stringers and is mainly associated with pyrite, pyrrhotite, chalcopyrite, and arsenopyrite. Most sulphides occur as disseminations and fine stringers sub-parallel to the foliation fabric suggesting development in active shear zone or re-mobilization. Magnetite and graphite are present locally. Although the sulphide content can be as much as 5%, it is on average only 1% to 2% in fresh (i.e., non-weathered) mineralized rocks.

Gold mineralization is hosted by various rock types but most commonly in the biotite schist (meta-gabbro) and its host rocks (typically the meta-sandstones but also the granodiorite dykes that intrude the gabbros), although in Maga north, P16 and P17N areas, the metaargillites are the main host. The syn-tectonic granodioritic intrusives are also mineralized, although to a lesser degree than the biotite schist and the meta-argillites. The metaconglomerate and meta-peridotite are unfavourable hosts. The meta- gabbro might represent the best chemical trap given its high iron content if gold was transported as a thiocomplex, as suggested by the pervasive fine pyritic assemblage that is associated with the gold mineralization in the sulphide zone. Although much of the gold resources defined within the Project area are hosted in the meta-gabbro unit, the deformed granodiorite and its contact zone with the meta-gabbro host is where the better-grade mineralization is concentrated.

At a cut-off grade of approximately 0.2 g/t Au, the gold mineralization exhibits reasonable continuity over a strike length of approximately ten kilometres. At this cut-off grade, the gold mineralization forms more restricted corridors (500 m to 1,000 m in length and 10 m to 100 m in width) defining anastomosing patterns, parallel and slightly oblique to the general trend of the BSZ.

These higher grade corridors formed the basis for defining geostatistical domains within each litho-domain considered for resource estimation. One of the benefits of the 2010 to 2013 infill drilling programs was the delineation of higher grade sub-domains based on a cut-off grade of 0.5 g/t Au with the broader low grade domains based on a lower cut-off grade of 0.2 g/t Au. The higher grade sub-domains have a strike length of up to 500 m and a width typically between 5 m and 30 m.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityUnitsAvg. Annual (Projected)LOM (Projected)
Gold koz 1341,600
All production numbers are expressed as metal in doré.

Production Costs

Commodity production costs have not been reported.

Heavy Mobile Equipment

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Personnel

Mine Management

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