Fosterville Gold Mine has marked its two millionth ounce produced, a symbol of its transformed fortunes.
Managing company Kirkland Lake Gold's manager of Australian operations Ian Holland said the operation was transformed by the discovery of a high grade ore deep underground.
He said the mine would produce 570,000-610,000 ounces of gold in 2019, compared to 350,000 ounces last year.
Mr Holland said Fosterville had four to five years worth of high grade reserve still to mine at its current rate of production.
And he flagged future expansion, as Fosterville explored its lease.
Fosterville Gold Mine general manager Ion Hann said the mine hadn't always been a "cash cow".
It used to have a low margin, producing just about 100,000 ounces of gold a year, he said.
Mr Hann said the two millionth ounce was a recognition of the hard work put in by the mine's employees.
"It's been a tough mine for the initial part of the journey, so really the two million ounces now is vindication of the perseverance of all the people," Mr Hann said.
"It's [had] six owners since I've been on site. A number of them have come and gone.
"The last few owners have reaped the benefit of perseverance from early days."
Fosterville is now owned by international mining company Kirkland Lake Gold.
Mr Holland said the discovery of a quartz ore body further underground, with visible gold, had driven the mine's success.
It has produced a total of $4 billion worth of gold at today's price, Mr Holland said.
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"The operation was transformed by the discovery of high grade gold at depth," Mr Holland said.
"The first million ounces came in 11 years, through until 2016. The second million ounces came in a bit under three and a half years.
"The reason for that is that the grade of our ore body started to increase at depth, and that was really exciting for us."
Mr Holland said the mine had four to five years of reserves, but was still committing to further exploration.
He said drilling at Robins Hill in the northern part of the lease had been successful, meaning the mine saw it as a potential future production point.
The mine was exploring across its 28 square kilometre lease.
It also had 1400 kilometres of exploration tenure, he said.
"We're still really in that growth phase that we're seeing as a result of that high grade [discovery]," Mr Holland said.
"Our reserves are at 31 grams per tonne, that's exceptionally high grade, in fact it's the highest grade gold mine in Australia, and one of the highest grade gold mines in the world."
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