History
The history of Stawell Gold Mines
Stawell Gold Mines (SGM) has a rich history dating back to the mid-19th century gold rush, when the region became a hub for prospectors. Over time, mining operations evolved from surface prospecting to deep underground mining. Modern operations began in 1981, with a focus on innovation and sustainability. Today, SGM continues to extract gold while prioritising environmental stewardship and community engagement.
The historical images below appear courtesy of the Stawell Historical Society.
1853
Gold was first discovered in Stawell.
1853-1926
An estimated 2.57 million ounces was produced from alluvial sources and from high-grade quartz reefs.
1873-1939
The Stawell Town Hall was opened, the landmark clock tower was constructed in 1939.
1938
A Pioneer’s memorial was erected on Big Hill.
1953
The Quartz Memorial and Dane Memorial seat were erected on Big Hill out of local quartz stone.
1969
The animated pair of gold prospectors operating a gold cradle was added to the Town Hall clock tower as part of Stawell’s centenary celebrations. The movement of the Miners is timed to occur at the same time as the clock chimes to play the tune, ‘With a swag upon my shoulder.’
1981
SGM opened. The population of Stawell was 6,160.
1984-1992
The modern production era began when a when a WMC/Central Norseman Gold joint venture opened SGM. Approximately 336,000 ounces of gold was produced. The population of Stawell sat at 6,640 in 1992.
1992 and 2007
1.4 million ounces of gold was produced at the mine.
1992-June 2005
MPI and Pittston acquired SGM.
2005-January 2007
The subsequent Leviathan Resources took ownership.
January 2007
Perseverance Corporation acquired SGM.
18 February 2009-October 2011
Northgate Minerals Corporation took over, and 2 million ounces of gold was produced.
October 2011-November 2016
SGM’s ownership transited a number of corporate mergers and acquisitions.
2015-2017
Kirkland Lake acquires the mine.
December 2016
SGM was placed in Care and Maintenance, with Kirkland Lake Gold holding ownership at the time. The population of Stawell in 2016 was 6,032 people.
December 2016-December 2017
The mine was placed in to care and maintenance as a new owner was sought.
December 2017
Private equity group, Arete Capital Partners negotiated a controlling interest in SGM and related assets, with the intention of returning the site to production by expanding the existing exploration programs to build the mineral inventory for the site.
2018-2019
A period of recommissioning the processing plant and re-starting of exploration and underground mining operations took place.
December 2018
First production firing since reopening.
31 January 2019
The first gold pour, since reopening.
2021
The Census showed a 4.8% growth from 2016 to 2021 in Stawell, with the population growing to 8,504 people.
METALLURGY
Mill processing facility
The mill processing facility at Stawell is highly flexible, able to process a wide variety of ore. It is set up to use a conventional gravity/leaching process, which recovers gold from both underground material and surface oxidised ore sources. The process involves a two-stage crushing, milling and a Carbon in Leach (CIL) circuit.
Coarse gold (up to 30% of the gold in mill feed) is recovered from the milling circuit in self-cleaning centrifugal gravity concentrators from the underground ore. Surface oxide materials from the open pits typically produce less gold as a percentage through-put via the gravity recovery system.
The majority of ore types require further liberation of the gold from sulphide. This is achieved in a two-stage flotation circuit where gold-bearing sulphides (e.g. pyrite, arsenopyrite and some pyrrhotite) are concentrated. The sulphide concentrate is ground to approximately 10 µm in an ultra-fine grinding mill to liberate enclosed gold (up to 20% of the gold in mill feed). The ground sulphides and flotation tail are recombined and sent to the CIL circuit, where sodium cyanide is used to leach the gold from the slurry.
The mill processing facility is capable of processing approximately 1,000,000 t/year, with a gold recovery of 85-90%. Gold recovery rates can vary depending on the quality of water used during processing and other factors, such as pH and temperature.
MINING
Underground workings
Underground mine production is serviced by the Magdala Decline, which has its portal access located adjacent to the mill processing facility.
The Magdala Decline ramps down at an average gradient of 1:8 and follows the gold bearing system known as the Magdala Lode. The decline is approximately 5.5 m high x 5.5 m wide and provides access to the ore body, a route for mine ventilation and mine services such as power reticulation and pumping systems. At -900 m RL, the decline splits into two routes, and services the Golden Gift Lode and the Magdala Lode from there on. In December 2012, the decline faces reached their lowest depth to date of -1,646 m RL and 1227 m RL respectively.
The predominant underground mining method used is sub level retreat bench stoping, utilising combinations of cemented rock fill and raw waste fill to maximise ore recovery. Stope sizes typically range from 2,000 t to 10,000 t, whilst production rates have varied over the course of the years.
In November 2023, SGM applied for and received and administrative notification to allow the mining of the Wonga underground area.
In October 2024, SGM processed the first ore from the Wonga Mine, accessed through the underground network of tunnels.
GEOLOGY
Geological setting
SGM is situated near the western margin of the Stawell Zone of the Lachlan Orogen. This margin is defined as a north-northwest trending, complexly deformed shear zone system that is bound by the Moyston Fault to the west and the Coongee Fault to the east.
Lithologies are Cambrian to Ordovician in age and are dominated by schists that grade from lower amphibolite facies in the west to greenschist facies to the east. Dispersed through these facies are felsic to ultramafic igneous intrusions (eg. Stawell Granite) and isolated mafic volcanic domes. The western margin of one of these domes (Magdala Dome) hosts the Magdala Deposit at Stawell.
Gold mineralisation at Magdala is coincident with an extensive structural and hydrothermal event in the western Lachlan Orogeny. This event occurred at approximately 440 Ma and is contemporaneous with the deposition of the famous gold lodes of the Bendigo-Ballarat zones (Arne et al 2001, Phillips et al. 2012). There are three separate ore bodies defined at Stawell; Magdala, Golden Gift and Wonga ore bodies.
The Magdala ore body hosts three dominant ore types Central Lode, Basalt Contact Lode and Stockwork Lodes. The Central Lode is a quartz rich shear lode ranging from 0.5 to 10m in width and dipping 55-65˚ to the west, which was a significant historical production source in the Magdala Mine. The Central Lode is approximately 4km in strike with 1km of dip extent comprising variable mineralised shoots that are >4.0g/t. These shoots vary from 20m up to 200 to 350m in strike. Free gold occurs in the quartz or associated with pyrite, arsenopyrite and recrystallised pyrrhotite. The Basalt Contact mineralisation, typically 2 to 3m wide, is represented by arrays of quartz sulphide tension veins immediately adjacent to the volcanogenic basalt contacts.
The Golden Gift consists of one distinctive ore type, aptly termed the Golden Gift Stockwork. This mineralisation style contains a spectrum of all styles seen at Magdala with typical widths ranging from 8 to 12m (but can be up to 30m) and the strike extent of shoots ranging between 150 and 400m. The Quartz content is generally below 25% and mineralisation includes abundant recrystallised pyrrhotite, coarse grained arsenopyrite, pyrite and visible gold.
The Wonga deposit is hosted within the informally termed Wonga Schist (part of the Leviathan Formation) along two main fault systems. The two fault systems controlling the mineralisation are the hanging-wall structure, which strikes towards 350˚ and dips between 25˚ and 50˚ towards the east, and the link structures, which generally trend toward 240˚ and dip between 40˚ and 70˚ to the southeast. Wonga mineralisation occurred during late-stage magmatic events associated with the emplacement of the Stawell Granite ca. 400 Ma.