The South Kalgoorlie Operations are located in the Eastern Goldfields Superterrane of the Archean Yilgarn Craton. The SKO tenement package falls largely within the Kalgoorlie and Kurnalpi Terranes, which in turn are further subdivided into several structurally bound domains, which preserve distinct volcanism.

Stratigraphy for the Ora Banda and Kalgoorlie Domains is relatively well-known and comprises (from stratigraphically lowest) a lower basalt unit, komatiitic to high-magnesian basaltic rocks, an upper basalt unit and overlying felsic volcanic-sedimentary units. Conglomeratic and sandstone units unconformably overlie the upper felsic units adjacent to major shear zones. Layered mafic sills occur within various stratigraphic units and cross-cutting Proterozoic dykes also occur throughout the region. Metamorphic grade ranges from upper greenschist to upper amphibolite facies.

The deformation history of the area is generally divided into four main phases, comprising north directed thrusting with recumbent folding and stratigraphic repetition in D1. The second deformation (D2) resulted in north-northwest trending folds which are reflected in the dominant north-northwest trending fabric of the greenstone belts. Shortening continued during D3 with strike slip movement along northwest to north-northwest trending shear zones and D4 brittle faulting.

Mineralisation is common in shear zones along lithological contacts. Discordant veins may be grossly stratabound and restricted to specific lithologies. Deposits may run the complete spectrum from ductile to brittle fault and fracture zones though most goldhosting structures show features of brittle-ductile transition. While all Archean lithologies in Yilgarn greenstone belts may be mineralised, mafic volcanics and internal granitoids are the most productive hosts in areas of significant gold production.

Mining from the HBJ underground commenced last financial year with the operation ramping up to stope production 4QFY16. Mining required a new portal and decline into the existing underground operation with historic underground infrastructure refurbished. Mining utilizes longhole open stoping.

Mining from surface will be sourced from a number of open pit mines that include the Trojan pit, Location 59 pits and Penfolds pits.

Processing is through a CIL plant with ball mill name plate capacity of 1.2mtpa. Recoveries are expected to be in the order of 90% now the ramp up is complete and this has already been completed during the ramp up phase last year despite lower than expected head grades.

Throughput and general processing performance has beaten expectations through FY16 despite delays mining HBJ.