Anglo-Swiss miner Xstrata (XTA.L: Quote) reported a 6 percent decline in copper output in the first quarter due to severe weather conditions at its Collahuasi mine in Chile and lower grades at its Alumbrera mine in Argentina. Overall, the miner said adverse weather conditions including flooding in Queensland and Western Australia, tropical cyclone Yasi and heavy rainfall in South Africa, Colombia and other parts of South America impacted production during the period.