Ninety Waihi miners will walk off the job on Saturday evening, demanding better pay.
The 48-hour strike, set to begin at 7:15pm, could be the first of many by OceanaGold employees.
"The company's doing really well, and they've got to share that with the workers," E tū union organiser Myles Leeson.
He says recent surveys have found seven times more gold than was expected.
"They need to remember who digs that gold out of the ground for them and reward them with a fair pay rise."
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Mr Leeson says a new roster to reduce the "excessive hours" the miners work has come with pay cuts of up to 19 percent.
"They've accepted this and are comfortable with it. They've been working ridiculous hours to get a decent wage. So, they need a fair pay rate, so they can earn a living without unsafe working hours."
Newshub has contacted OceanaGold for a response to the union's strike notice.