WA Leonora

Gold areas represent exploration licences.

In the Leonora region, exploration is focused on defining additional ore sources to supplement production from Gwalia. This is similar to strategy pursued with the new King of the Hills mine where ore is trucked to the Gwalia mill for processing. Another advanced opportunity is the Tower Hill deposit, presently subject to detailed investigations.

Gwalia

The Gwalia deposit has produced over 4 million ounces over a long history dating back to 1897. Mineralisation is hosted within an east-dipping series of basalts and dolerites. Multiple strongly mineralised en-echelon lodes are present which trend NNE over a strike length of 500m, and maintain strong down-plunge continuity.

Resource definition drilling by St Barbara leading up to development was focused on the South Gwalia Series and South-West Branch lodes, which host the bulk of the reserves. Positions such as the Main Lode, Hangingwall Lode, and West Lode represent extensional targets immediately along strike from existing resource. The ore body also remains open at depth.

King of the Hills

King of the Hills mine (formerly referred to as the Tarmoola higher grade, underground project) is located 42km to the north-west of Gwalia. The project was approved for development in March 2010 and commenced operation in June 2011.

Like Gwalia, the project has a long history dating back to 1897 when high-grade underground mining first commenced at this location. Between 1985 and 2004, previous operators focussed on extraction of high volume, low-grade mineralisation through open pit mining, taking total production to 1.6 million ounces.

Mineralisation is predominantly associated with sheeted / faulted quartz vein sets within a granodiorite stock and an enveloping carbonated ultramafic unit where intersected by a major regional shear zone. Broad-spaced drilling has identified high-grade intersections around the margin of the granodiorite body up to 800m north to the existing resource, including 3.7m @ 33.5 g/t from 560 metres below surface and 5m @ 7.5 g/t from 514 metres below surface. These results support the potential to extend the mine life beyond 2016.

Gravity anomalies in the surrounding area suggest that additional concealed granodiorite stocks are present, representing analogues for similar styles of mineralisation where intersected by major shear zones. Further modelling of these anomalies is progressing to develop drill targets.

Tower Hill

In August 2007, St Barbara discovered high-grade mineralisation at Tower Hill, 2 kilometres north of the Company’s Gwalia gold treatment plant. Tower Hill had previously operated as an open pit mine, ceasing operation in 1989 with approximately 176,000 ounces recovered to a depth of 80 metres.

Gold mineralisation at Tower Hill is hosted within quartz veins in ultramafic rocks overlying the Raeside Batholith. Mineralisation extends over a one kilometre strike length, and dips moderately to the east. Significant intersections at shallow depths of ~135-250 metres below surface have been achieved, including 18m @ 4.2 g/t from 147m, 7.9m @ 8.2 g/t from 157m, and 6m @ 8.5 from 239m. Irregularities in the granite-greenstone contact appear to strongly influence the grade distribution and development of veining. Similar flexures have potential to host mineralisation elsewhere along the granite margin down-dip or along strike from Tower Hill.

Further work is being undertaken to better understand the geological controls over the high gold grade domains and the potential for extending the mineralisation at Tower Hill prior to mining and pre-feasibility studies.

Regional Exploration

Targets in the Lenora District continue to be prioritised through analysis of the structural geology coupled with detailed mapping of alteration systems. Programs are currently focussed on improving the chances of exploration success by developing a detailed understanding of the target analogues and gaining maximum value from previous exploration data, which includes extensive geophysical and geochemical surveys, and a large amount of historical drilling. Focus will be upon targets that are either under younger cover or where there has been minimal exploration at depth.

Map of Operations