Bloomberg reported that Freeport McMoRan (NYSE:FCX) has halted production at its Grasberg mine in Indonesia as about 50 workers blocked road access to the mine. Copper was on the rise following the news, jumping roughly 10 cents to $2.75 on the news. As Grasberg is one of the largest copper mines in the world, a stoppage of production certainly has the potential to affect copper prices. As quoted in the publication: About 50 workers blocked access to a road to the mine for the fourth straight day, and output was suspended starting Monday, while shipments from inventories continued. Freeport is the largest publicly traded copper producer. "Investors are keeping a nervous eye on a lingering work stoppage at Grasberg," Edward Meir, an analyst at INTL FCStone in New York, said in a daily report. "Clearly, this is something the markets are watching."