The Yanfolila Project is located in the Yanfolila greenstone belt along the eastern margin of the Siguiri Basin, which is part of the Birimian volcano-sedimentary series of the West African craton.
Gold mineralisation at the Yanfolila Project occurs in a deformed stratigraphic sequence of basalt, polymictic conglomerate, feldspathic sandstone, siltstone and greywacke. Mineralised mafic intrusive rocks are also present at some locations. Regional scale, cross-cutting faults and structural lineaments, as well as rheologically contrasting rock types, appear to control the localisation of gold. Mineralisation styles are dominated by vein, breccia and intrusive types. Lodes are characterised by intense albite-carbonate veining and pervasive sulphide alteration. Weathering and oxidation of the sulphide component generally extends to a depth of 30 to 50 metres, with a well-developed saprolite zone.