Copper traded in London dropped the most in almost two weeks on Tuesday on signs that economic performance of China, the world's largest user of the metal, is weakening as the outlook for growth was reduced by JPMorgan Chase & Co. August copper futures slipped by 2.3% to $7,241 a metric ton as of 11:32 a.m. on the London Metal Exchange, while July copper futures fell 2.2% to $3.287 a pound on the Comex.