The mine is located within the Obuasi concession area in southwestern Ghana along the north-easterly striking Ashanti volcanic belt. The deposit is one of the most significant Proterozoic gold belts discovered to date. The Ashanti belt predominantly comprises sedimentary and mafic volcanic rocks and is the most prominent of the five Birimian Supergroup gold belts found in Ghana.

Multiple lodes are a common feature. Mineralized shears are found in close proximity to the contact with harder metamorphosed and metasomatically altered intermediate-to basic Upper Birimian volcanics. The competency contrast between the harder metavolcanic rocks to the east and the more

Gold mineralization is associated with, and occurs within, graphite-chlorite-sericite fault zones. These shear zones are commonly associated with pervasive silica, carbonate and sulfide hydrothermal alteration and occur in tightly folded basement rocks.

Two main ore types are present, namely quartz vein and sulfide ore. The quartz vein type consists mainly of quartz with free gold in association with lesser amounts of various metal sulfides containing iron, zinc, lead and copper.

This ore type is generally non-refractory. The sulfide ore type is characterized by the inclusion of gold in the crystal structure of arsenopyrite minerals. Higher gold grades tend to be associated with finer grained arsenopyrite crystals; the sulfide ore is generally refractory.