Solidarity, along with three other unions, had been negotiating since December over wages at Sibanye's gold mines but said it did not take part in a union strike vote on Tuesday after deciding to accept the offer.
Under Sibanye's final offer - the sixth since talks began - miners, artisans and officials would receive a 5% pay increase each year and "unskilled and semi-skilled" employees would be given an increase of R800 a month for each of the three years, including a R100 a month increase in allowances.
Solidarity said that an "overwhelming" majority of its members accepted the final offer in a confidential vote.
"We are satisfied with the offer and are happy that we could negotiate this increase for our members," Riaan Visser, deputy general secretary at Solidarity, said in a statement.
The remaining unions in the coalition - the Association of Mineworkers and Construction Union (AMCU), National Union of Mineworkers (NUM) and UASA - have yet to announce the result of Tuesday's vote on whether to strike.
A Sibanye spokesperson declined to comment on Solidarity's decision, saying the company is awaiting the outcome of the ballot process.
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