Workers at the world's largest copper mine, BHP Billiton's Escondida in Chile, ended a lengthy strike Thursday that had caused turbulence on global markets.
But the company warned that the miners had only made matters worse by pushing negotiations back another year and a half.
With no breakthrough in sight in the testy negotiations, the miners' union decided to invoke an article of Chilean labor law that allows them to keep their old contract for another 18 months, union lawyer Marco Lopez told AFP.
Management at Escondida said triggering that law, known as Article 369, was a mistake.
"We know it's not good for anybody, and would be a complicated situation," the mine's president, Marcelo Castillo, said just before workers made the announcement.
Management had earlier announced the formal end of negotiations, giving the workers an ultimatum to take or leave its final offer.
Like other mining companies, BHP, which owns a 57.5 percent stake in the mine, is scrambling to cut costs amid a slide in copper prices in recent years.
It had rejected workers' demands for a seven percent raise and bonuses of 25 million pesos (around $38,000).
Instead, the Anglo-Australian mining giant was offering bonuses of 11.5 million pesos, with no raise.
The miners are also demanding to keep their current health and other benefits, and that new workers be given the same pay and benefits as existing ones.
The end of the 43-day strike came on the day it broke the record for the longest mining strike in the history of Chile, the world's top copper producer.
The workers will return to work Saturday, Lopez said.
- 'Worst thing' possible -
The miners' union declared Thursday "Mining Dignity Day" and announced it would hold festivities at the camp where the 2,500 striking miners had been picketing.
"We have protected the future of new generations of workers at this company," it said in a statement.
But industry analyst Gustavo Lagos warned the outcome was a win for no one.
"This is the worst thing that could have happened, because there will be 18 months of very bad relations" between workers and management, likely hurting production, he said.
The sprawling mine complex in the Atacama desert normally supplies some five percent of global copper output.
The company said the strike had dented production by between 3.6 million and four million tonnes.
The union estimated the cost to the mine was more than $1 billion.
- Bellwether strike? -
The Escondida dispute was seen as a bellwether in a year in which eight other major copper mines in Chile and around the world also face expiring contracts.
Including Escondida, the mines account for around 12 percent of the world's total copper supply.
But the outcome of the Escondida strike offered no clear signpost for how negotiations could play out elsewhere.
Article 369 is unique to Chile, and it is the first time a strike at a major mine has ended with workers invoking it.
Chile's situation is also unusual because the country has a new labor law entering into force in April.
The miners' union is clearly hoping the reform will increase its leverage. Under the new law, previously existing benefits will be the minimum starting point for future negotiations.
The workers appear to be betting that foregoing their signing bonuses and their lost wages from the strike will pay off in the end.
The union said new negotiations were now due to begin on June 1, 2018.