Copper
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Copper is used in many alloys. For example, brass is a copper–zinc alloy, and bronze is a copper–tin alloy. These alloys are extensively used in piping, electrical applications, architecture, the building industry, household products, coinage, biomedical applications, chemical applications and musical instruments.
The main ore of copper is chalcopyrite (CuFeS2), which is often associated with other base or precious metal ores, notably those containing gold, galena (PbS) and sphalerite (ZnS).
In Victoria, copper-bearing ores have been discovered in a variety of geological environments. These include deposits of exhalative volcanogenic origin, sulphide–quartz lodes in Ordovician sediments, deposits associated with dykes and granites, and concentrations in chemically reduced Carboniferous sediments.
Most of the copper ore in Victoria has been mined from four locations. In northeast Victoria, it has been mined at the Wilga mine near Benambra and from a high-sulphide zone west of Bethanga. Other deposits have been mined at Thomson River near Walhalla; and at Accommodation Creek near Deddick.
The Wilga copper mine has produced 45,810 tonnes of copper and is the largest copper mining operation in Victoria. Although it is yet to be exploited, the nearby Currawong deposit has a resource of 1.79 million tonnes of ore containing 3.14% copper. These two deposits are volcanic-hosted massive-sulphide zinc–copper deposits.
In the Bethanga district, northeast-trending gold-bearing reefs contain abundant sulphides. These structurally controlled reefs are up to one metre wide and contain pyrite, arsenopyrite, chalcopyrite and sphalerite.
Copper mineralisation at the Thomson River mine lies along a fault zone parallel to the western margin of a hornblende diorite dyke, and is also disseminated within the dyke. The fault zone mineralisation is from one to three metres wide and has been reported to contain 16% copper. Exploration in this area also revealed traces of gold, silver, platinum, palladium and nickel sulphides. More than 12,000 tonnes of ore was produced between 1865 and 1913, with estimated average grades of 3.8% copper, 0.3% nickel, 13 ppm silver, 1.5 ppm gold, 2.3 ppm platinum and 3.8 ppm palladium.
The Accommodation Creek copper mine is on a north–south trending shear zone within contact-metamorphosed Ordovician sediments, adjacent to the Deddick Granodiorite. The mineralisation consists of chalcopyrite within a gangue of quartz, barite and calcite.
At Mount Ararat in western Victoria, there is an inferred resource of approximately 1 million tonnes containing 2.7% copper in massive, banded and disseminated chalcopyrite–pyrrhotite–sphalerite ore. The Mount Stavely prospect, southwest of Ararat, has an inferred resource of 10.6 million tonnes containing 0.45% copper, which could conceivably produce 47,300 tonnes of copper. There is also copper mineralisation associated with acid volcanic rocks in the Buchan and Limestone Creek districts.
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Further information
- Copper, gold and nickel discovery opportunities in and around the Dimboola Arc Domain - GSV Technical Record 2009/1
- Minerals of Victoria - Geological Survey of Victoria Report 92
- Geology of Victoria - Geological Society of Australia
