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Macraes mine, New Zealand

10th July 2015

By: Sheila Barradas

Creamer Media Research Coordinator & Senior Deputy Editor

  

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Name: Macraes mine.

Location: The Macraes mine is located north of Dunedin, in the Otago region of the South Island of New Zealand.
Controlling Company: OceanaGold Corporation through its wholly owned subsidiary OceanaGold.

Brief History: The original tenements at Macraes were owned by Golden Point Mining and BHP Gold Mines (New Zealand). In 1989, Macraes Mining Company acquired 100% ownership of the tenements. Macraes Mining changed its name three times – to Gold & Resource Developments in May 1999, to GRD Macraes in June 2000 and four years later GRD Macraes changed its name again to OceanaGold in 2004.

Brief Description: The Macraes mine is the largest gold-producing mine in New Zealand and comprises the Macraes openpit, which has been operating since 1990, and the Frasers underground mine, which was commissioned in January 2008. The operation includes an adjacent processing plant. The combined openpit and underground mines currently support a mine life of about eight years.

Products: Gold.

Geology/Mineralisation: The Macraes gold deposits are located within a low-angle shear zone, the Hyde Macraes shear zone (HMSZ), which has been traced for at least 30 km along strike. The HMSZ contains the variably altered, deformed and mineralised Instrashear schist up to 150 m thick.
The thickest part of the shear zone consists of several mineralised zones stacked on metre-thick shears. These shears have ductile deformation textures overprinted by cataclasis. The Hangwall shear can be up to 20 m thick and is commonly darker, owing to the fine-grained graphite and sheared sulphide minerals.
According to the mine’s technical report released in 2010, there is a strong empirical correlation between gold, arsenic, scheelite, silification and strain intensity in the HMSZ.
Gold/scheelite/pyrite/arsenophyte mineralisation is associated with replacement and fissure quartz veins in postmetamorphic shear zones. Shear parallel quartz veins and cataclastic shears contain the highest gold and scheelite grades.
Reserves: Total proven and probable reserves as at December 31, 2013, were estimated at 42.03-million tonnes grading 1 g/t of gold.
Resources: Total measured and indicated reserves as at December 31, 2013, were estimated at 117.3-million tonnes grading 1.06 g/t of gold. Inferred resources were 65-million tonnes grading 1 g/t of gold.
Mining Method: Macraes is mined using a combination of conventional openpit and underground retreat uphole stope methods along the line of strike. The openpit operation is owner-operated, while the underground operation is mined under an alliance agreement, with OceanaGold providing management and technical guidance for the mining contractor who performs the physical mining tasks.

Major Infrastructure and Equipment: The Macraes operation comprises a large-scale openpit mine, an underground mine and an adjacent processing plant.
The openpit operation uses hydraulic excavators and rear dump diesel trucks to extract overburden and ore.
The underground retreat uphole stoping mining operation uses electrohyraulic development jumbos, diesel load-haul-dump units, diesel haul trucks and a production drill rig to extract waste and ore.
At the processing plant, the ore undergoes crushing, grinding, flotation, fine grinding, pressure oxidation carbon-in-leach, elution, electrowinning and smelting.
Prospects: Among other initiatives, further exploration drilling targeting the deeper extensions of the Macraes orebody is ongoing to identify and develop additional underground mines along the strike of mineralisation. Exploration is also targeted at other potential surface mineable targets along the Macraes’ line of strike.
Contact Person: Media relations, Andrea Atell.
Contact Details:
tel +61 3 9656 5300,
fax +61 3 9656 5333,
email info@oceanagold.com, and
website http://www.oceanagold.com.

Edited by Leandi Kolver
Creamer Media Deputy Editor

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