Geology

The Perkoa project area is located in central Burkina Faso, West Africa in the central part of the Boromo greenstone belt, which comprises volcanic and sedimentary rocks of the Lower Palaeozoic Birimian Supergroup. The Birimian greenstone belts are renowned for their occurrences of economic gold mineralisation, such as the world class Ashanti gold deposit in Ghana. The Perkoa deposit represents the only significant zinc-silver massive sulphide mineralisation that has been discovered in the Birimian Supergroup to date.

The type of mineralisation at Perkoa is volcanogenic massive sulphide (VMS) and consists of two sub-parallel sulphide-rich bodies (the footwall and the hanging wall bodies), both occurring within rhyolitic tuffs. The footwall body contains a massive sulphide zone with a strike length of 300m, ranging from 1m to 30m in width and extending from a minimum depth of 25m to a drill intersected depth of 550m below surface. The hanging wall sulphide body has similar dimensions to the footwall sulphide body, but sulphide mineralisation is less massive and consequently of lower grade. The two sulphide bodies are separated by 10m to 60m of barren rhyolite tuffs. The sulphide lenses dip at approximately 60° to 80° to the northwest.

Intrusive bodies cut through and truncate the mineralisation in places, although no faults have been identified by the exploration. A full assessment of the structure can only be carried out when the mineralised zone is exposed by underground development. 

The sulphide mineralisation is primarily pyrite and sphalerite with lesser amounts of pyrrhotite. Minor sulphides include galena, arsenopyrite and chalcopyrite. The mineralised zones also contain large amounts of barite.