The rock sequence at the Sukari Gold Mine comprises part of the Neoproterozoic Arabian-Nubian Shield, one of a number of areas of African continental crust that accreted and stabilised during the Pan-African Orogeny.
At a district scale, the host sequence at Sukari comprises a north-north-east striking melange of predominantly calcalkaline igneous rocks and metasediments representing an accreted island arc or arcs. Very weak oxidation is generally to a depth of 10-20 metres and there is also weak oxidation to 50 metres plus down narrow shear zones and faults. The bulk of the resource is in fresh unoxidised (sulphide) rock.
Sukari is a large, sheeted vein-type and brittle-ductile shear zone hosted gold deposit developed in a late to post-orogenic granitoid intrusive complex. Gold mineralisation is hosted exclusively by a granitoid body of approximately granodiorite-tonalite composition. Gold mineralisation is intimately related to sulphides; pyrite is the most abundant sulphide, followed by arsenopyrite. High gold grades are associated with arsenopyrite concentration.
The sulphides occur as fine grained, subhedral disseminations in altered porphyry and as blebby sub- to euhedral crystals and finer disseminations in quartz veins, fractures and breccias. Visible gold occurs as anhedral grains in milky white extensional and breccia quartz veins and as intergrowths with pyrite and arsenopyrite, commonly in narrow shear veins at quartz vein margins and margins to clasts in hydraulic quartz vein breccias.
The deposit has a strike length of approximately 2.3km and ranges in thickness from 100 metres to approximately 600 metres. Mineralisation has been intersected down dip to depths of 1200 metres below the wadi (valley) surface level.