Its copper mines are said to be capable of yielding 500,000 tons a year; they now yield no more than 50,000.

"Not in Brazil or anywhere else are you going to find two crops a year yielding three tons of grain an acre."

These seams yield 5,000 to 5,800 tons of coal an acre.

The deal is expected to yield about 7.8 million tons of liquefied natural gas a year for 25 years.

The coprolite was worth about £3 a ton in 1890, yielding some 300 tons per acre.

By 1985, however, 385,900 hectares were covered with cotton, yielding almost 159,000 tons.

In 1994, about 50 campsites yielded 120 tons of trash.

Consolidated yielded almost 300,000 tons of copper between 1819 and 1840 which sold for over £2 million.

The crop is expected to yield more than 6,500 tons of opium, exceeding global demand.

The country's 51 gold mines last year yielded 640 tons, which accounted for 60 percent of foreign exchange earnings.