Production at the Rustenburg mine was disrupted for eight weeks in 2012 following illegal strike action.

BBC: Amplats plans 6,000 job cuts in South Africa

That might help explain why New York City's transit workers were willing to wage an illegal strike last month.

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"Equivalent refined platinum production decreased by 29% owing to the illegal strike action at the Rustenburg, Amandelbult and Union mines, " the company said in a statement.

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