BLAIR Athol workers stand to miss out on up to $100,000 in redundancy payments when the Rio Tinto mine closes on November 23, according to the CFMEU.
District vice president Glenn Power said 26 of the 29 unionised workers at the mine voted on Monday to strike for what he termed a "fairer deal".
The union is yet to file official notice with the company, but union representatives will meet today to strategise the industrial action.
"There should be no segregation and disparity between the payments," Mr Power said.
There is a substantial amount on the line - CFMEU's Glenn Power
"We want a fairer deal."
Mr Power said the difference between union and non-union workers amounted to as much as $100,000, with one case in particular tallying up the Role Allowance accrued over the past 30 years.
He said redundancy payments to two workers who had worked virtually side by side over the life of the mine in the same role were unfair.
The only difference between the workers, Mr Power said, was one belonged to the CFMEU, and the other did not.
"It's really frustrating to see an employer like Rio Tinto overlook equal rights and equal opportunity, which they push for," he said.
The CFMEU is investigating potential litigation in court in an attempt to secure the same deal for its members, he said.
While the union has yet to file notice with Rio Tinto, Mr Power said any stoppages would deliver the most impact on the closing mine. But Rio Tinto said there would be minimal disruptions to Blair Athol's operations.
"We have plans in place to minimise disruptions using the remaining workforce and operations at Blair Athol are expected to finish as scheduled this month," a company spokesman said.
"Rio Tinto respects the right of employees to choose whether or not they take protected action."
The spokesman maintained the company had bargained the enterprise agreement in good faith and was disappointed the CFMEU had "chosen to encourage industrial action".
"Employees who have chosen to be on this collective agreement have benefited from a number of secure working conditions and benefits over many years," the spokesman said.
"Rio Tinto believes the proposed agreement, including the redundancy payments, is fair."