Copper rose half a percent in London and Shanghai on Wednesday, gaining in the shadow of a growing strike threat at one of the world's biggest copper mines, Chuquicamata in Chile. Worries about supply ratcheted up a notch after union workers at Chile's massive Chuquicamata copper mine complex rejected an early wage offer from owner Codelco on Tuesday.
A vote on a final offer is expected before the contract expires on December 31. If rejected, a strike could come as early as the first week of January. The precarious nature of the copper concentrate market was underscored by reports that Freeport McMoRan had inked annual treatment charge deals with Japanese smelters 38 percent down from 2009 levels. "You are talking $200 in fees and premiums to convert concentrate into cathode. Out of that you need to pay your energy and wage bills and get the cathode shipped. It's not an attractive business right now," a dealer in Singapore said.