Name: Reefton mine.

Location: The Reefton mine is located 7 km south-east of the Reefton township, a historic mining district, in the West Coast region of New Zealand’s South Island.

Controlling Company: OceanaGold (New Zealand), a wholly owned subsidiary of OceanaGold Limited and OceanaGold Corporation.

Brief History: Alluvial gold was first discovered in the Reefton area in 1866, at the zenith of the West Coast gold rush. Efficient dredging operations of the local rivers and tributaries from 1900 to 1913 and from 1934 to 1957, and alluvial mining from 1980 to 1997, have led to about eight-million ounces of gold being recovered.

Brief Description: The Reefton mine comprises a series of openpits developed along a major regional shear structure and its offshoots. Globe Progress is the largest sulphide-associated deposit currently known in the Reefton goldfield.

Products: Gold.

Geology/Mineralisation: Gold mineralisation in the Reefton goldfield is orogenic-style and the deposits occur in and around steeply dipping, north- to north-north-east-trending shear zones that cut across the hinges of earlier folds in weakly altered metasedimentary rocks. The deposits are similar in many respects to those found at Bendigo and Ballarat in Victoria, Nova Scotia, Canada; Beaconsfield, in Tasmania; Gympie, in Queensland, Australia; and the ‘Mother Lode’ deposits in California, the US.

Most of the gold-bearing mineralisation, including all the larger deposits, is arranged along a linear belt, which runs north to south through a sequence of deformed metasedimentary rocks of the Greenland group. This suggests the presence of a deep-seated structure that has permitted mineralising fluids to migrate from their source to sites in the upper crust where the gold was deposited.

The two dominant styles of gold mineralisation in the Reefton goldfield are coarse native gold associated with minor sulphides in quartz veins, and microscopic refractory gold in sulphides in sheared sediments and in clay alteration (pug) zones adjacent to the quartz veins.

The coarse native gold style of mineralisation comprises the majority of historical gold production. Both styles, however, provide important exploration targets.

Reserves: Total proven and probable reserves as at December 31, 2013, were estimated at 4.24-million tonnes grading 1.43 g/t of gold.
Resources: Total measured and indicated reserves as at December 31, 2013, were estimated at 15.5-million tonnes grading 1.5 g/t of gold. Inferred resources were 7.8-million tonnes grading 3.7 g/t of gold.

Mining Method: Conventional openpit mining along the line of strike.
Major Infrastructure and Equipment: The major site infrastructure includes openpits, a tailings storage area, waste rock disposal areas, a process plant and access roads.

At the Reefton processing plant, ore undergoes crushing, grinding, flotation and concentrate dewatering. Throughput is currently 1.7-million tonnes a year. Refractory concentrate produced from the Reefton processing plant is transported by road and rail to the Macraes mine processing plant for treatment through the autoclave pressure oxidation and carbon in cyanide leaching.

Prospects: In the quarter ended March 31, OceanaGold initiated a brownfield exploration programme at Macraes to increase its resource base and further increase the mine life at current production rates and with good margins.

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.