A strike for a R12 500 monthly wage by Rustenburg platinum mine workers spread to the chrome sector on Monday.
Workers at Samancor said they had been on strike since Friday.
"We demand R12 500 pay after deductions. This excludes bonuses," said Lawrance Kok, one of the workers' leaders.
He said they also demanded a R1500 sleep-out allowance and a R1500 underground allowance.
Comment from Samancor was not immediately available.
Last week, Anglo American Platinum (Amplats) and Aquarius Platinum, in Rustenburg, suspended operations for the safety of their workers.
However, groups of workers gathered at Amplats' Blesbok stadium said it was not a suspension but a strike.
On Friday, workers marched to Aquarius Platinum demanding that it shut down. They said they aimed to have all mines in the area closed this week.
On Monday, Aquarius Platinum said it had resumed operations and that none of the seven people arrested by police during an illegal gathering outside the mine on Friday were employees.
On page two... workers at Lonmin's Marikana mine were the first workers to demand a R12 500 increase....