East Otago, having produced more than 4.4million ounces of gold in that period.
During the past quarter century, billions of dollars have been poured in the Otago economy and national trade receipts from the extraction of more than 124 tonnes of gold since opening in 1990. That most recently includes production from Reefton on the West Coast and the Philippines.
Through numerous company incarnations from Macraes Mining, to GRD Macraes to the present Oceana Gold, the company has, during the past three years, become one of the most successful mid-tier miners in the world, largely from having persevered with developing its gold and copper mine in the Philippines, Didipio, on the northern island of Luzon.
That perseverance saw Oceana this year awarded the prestigious Diggers Award at the Diggers & Dealers annual conference in Kalgoorlie - a rare feat for a company with no Australian mining assets.
However, the recent inclusion of Waihi in the central North Island and development gold mine Haile in South Carolina are now expected to cement Oceana's claim to become the top mid-tier miner.
Oceana's chief executive, Mick Wilkes, said while Macraes and Reefton were the ''foundation'' for Oceana, Didipio became the ''big transformation'' for the company, in what he has recently described as the ''new Oceana Gold''.
''With Didipio and now Waihi and Haile, we want to become the mid-tier miner of choice ... we're already a long way into being that company in that sector,'' Mr Wilkes said in an interview in Dunedin.
''Its been a big transformation over the past four years, making us into a multinational,'' he said.
The cost to produce an ounce, which creates the similarly just as crucial free cash flows, is foremost for Mr Wilkes.
He is predicting that by 2017 Oceana will be producing more than 550,000oz annually at an ''all in sustaining cost'' of less than $US600 ($NZ913) per ounce.
''That's one of the lowest, if not the lowest in the world,'' Mr Wilkes said.
While the new developments overseas underpin Oceana's future momentum, the company has through wages, salaries and contract work annually pumped hundreds of millions of dollars through Otago's economy, and similarly, its West Coast Reefton mine for the past eight years.
At one point, Oceana's more than 600 East Otago staff contributed about $300million from wages into the economy in one year.
Didipio, which had to be put on hold during the 2006-07 global financial crisis, and the subsequent 25% gold price slump, most stretched Oceana, Mr Wilkes said.
''Getting Didipio completed was a bit tight financially,'' he said.
The 2015 calendar forecast for gold and copper production is 380,000oz to 410,000oz of gold from the combined New Zealand and Didipio operations, including 22,000 tonnes to 23,500 tonnes of copper.
Mr Wilkes said the copper, produced as by-product at Didipio, was worth the equivalent of 120,000oz of gold and was ''a very substantial revenue'' for Oceana.
Similarly, a tungsten-gold feasibility study is under way at Macraes at present.
This week, positive maiden drilling results were announced from Coronation North at Macraes, which Mr Wilkes said had the potential to extend mine life by ''one or two years''.
He remains upbeat about the longevity of Macraes, and while having to be circumspect on predictions, highlighted an almost doubling of exploration spending in New Zealand to $US10million.
''We're hopeful of adding [overall] three to five years to mine life,'' Mr Wilkes said.
Didipio is now going underground, to a depth of 750m below the pit floor, which under an optimisation study will be a ''huge saving'' in not having to remove 67million tonnes of waste rock, Mr Wilkes said.
That project has $US120million tagged for development, with production forecast by 2018.
Mr Wilkes is bullish on the outlook for the new Haile development, acknowledging that the potential to go underground was identified ''from the start of due diligence''.
''We do see [going] underground having plenty of upside potential for significantly more [estimated] reserves,'' Mr Wilkes said, with expectations that a feasibility study will be complete with 12 to 18 months.
Similarly, Waihi is ''looking promising'' and while not ruling out reopening of the historic Martha pit, exploration is focused on underground operations, Mr Wilkes said.
Macraes timeline
1862: Some alluvial mining around Macraes, gold found at Murphy's Flat, Macraes Flat and later Horse Flat.
1889: Golden Point and Round Hill discovered.
1890-1933: Around Macraes goldfield, Golden Point yields estimated 13,000oz gold and 800 tons scheelite. Prospects Maritana, Golden Bell and Deepdell yield 1630oz.
1980s: Hopgood brothers Owen and Eric (Golden Point Mining) prospect Round Hill, which later becomes the wider Macraes mine.
1989: Original Macraes tenements sold by Golden Point Mining and partner BHP Gold Mines (New Zealand) to the Macraes Mining Company Ltd.
1990: Macraes Mining Co begins production at Macraes' open pits. (Macraes Mining changes name to Gold and Resources Development Ltd in May 1999, changed again to GRD Macraes in June 2000).
1991: Reefton, West Coast, and Sams Creek acquired from CRA Exploration Ltd (Rio Tinto).
1999: Pressure oxidation and autoclave facility commissioned at Macraes, one of just three in the southern hemisphere. Credited with turning around production from low grade ore.
2003: Oceana Gold incorporated, (from GRD Macraes) dual-lists following year on NZX and ASX.
2005: 2 millionth Macraes ounce poured.
2006: Merger with Australian Climax Mining, to take over development of Didipio gold-copper mine, Luzon, Philippines. Climax principal James Askew, later becomes Oceana chairman.
2007: Oceana takes principal listing to TSX. Reefton open pit opens.
2008: Frasers underground at Macraes commissioned, GFC prompts mothballing of Didipio development.
2010: 3 millionth Macraes-Reefton ounce produced.
2011-12: Didipio development recommenced, first production. 2013: Buys development gold/silver mine El Dorado from Pacific Rim Mining Corp in El Salvadore.
2014: In February, 4 millionth ounce poured, from NZ operations.
2015: Purchase of central North Island Newmont Waihi for $132million. Acquisition of Romarco Minerals' gold development mine in South Carolina for $996million (Oceana script-only). Reefton to be put into care and maintenance.
2015+: Oceana expected to complete feasibility on Blackwater mine redevelopment at Waiuta, West Coast, and feasibility study on Macraes tungsten-gold project.
2015+: Areas at Macraes still being worked include Coronation, Deepdell, Golden Point, Round Hill, Southern Pit, Innes Mills, Frasers (pit and underground) Golden Bar and Taylors, covering about 27,500ha.
Estimated mine lives: Macraes pits, beyond 2017, Macraes, Frasers underground, beyond 2016, Didipio 2030. Reefton, ends 2015. Waihi (Correnso underground) 2018.
