The workers will be hoping for hefty pay rises, following a 37% rise in wages given by Freeport McMoRan Copper in December 2011 to end a three-month strike that had paralyzed output and lifted copper prices.

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Freeport may have lost 35 million pounds of copper and 60, 000 ounces of gold production during the strike.

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Virga said if the Grasberg strike is extended again, an additional 15 to 24 million pounds of copper production could be lost.

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