Copper Costs Turn Negative for Southern, Vale as Gold and Silver Byproducts Soar

For copper miners Southern Copper Corp. and Vale SA, surging prices of byproducts like gold and silver are creating an unusual situation: The cost of producing the red metal has turned negative.

Southern Copper reported a cash cost, net of revenue earned by selling byproducts, of minus 11 cents a pound in the January-to-March period, versus 77 cents a year earlier. That means the company is making money just by extracting copper ore from mines, even before accounting for the selling price of the metal.