Rio Tinto said this morning it had failed to arrest a decline in the United States and Australia in mined copper output, which fell 6 per cent in the third quarter because of lower metal content in its ore, driving its Australian share price down.
Coal output was also lower at a time of high demand, with steel mills and power generators vying for limited supplies. "It was a surprise to see almost everything down," said ABN Amro analyst Warren Edney.
The world's third largest miner by market capitalisation reported a 30 per cent rise in third-quarter refined copper production as it tried to capitalise on the global boom in industrial raw materials.
Rio shares closed down 3.5 per cent at A$110.00, outstripping an 0.18 per cent loss on Australia's S&P/ASX200 index.
Aluminium production was flat over the quarter, the company said.
Copper, found in everything from water taps to computer chips, is a key component underpinning analysts' profit forecasts of around $7.4 billion for the Sydney and London-listed company, accounting for nearly half of first-half profits.
Copper for delivery in three months on the London Metal Exchange has soared more than 25 per cent this year to above $8,000 a tonne, spurred on by high imports to China.
Iron ore was a distant second at 29 per cent of first-half earnings, with aluminium providing 11 percent of earnings during the period.
Rio's 30 per cent stake in the Escondida copper mine in Chile, the world's biggest, delivered 101,200 tonnes of contained copper and 16,100 tonnes of refined cathode.
Aluminium output was set to soar in 2008 to more than 4 million tonnes when Rio completes its $38.1 billion acquisition of Canadian producer Alcan Ltd to create the world's largest aluminium company.
Rio said its iron ore production and shipments in the third quarter were near record levels, with output in Australia 11 per cent ahead of 2006 for the first nine months of the year.