Santa Fe will exchange its coal and quarry assets for Hanson's Gold Fields Mining Company, which operates mines in Nevada and California.
Hanson will receive Santa Fe's Lee ranch surface coal mine near Albuquerque, New Mexico, with 700 million tons of coal, and six aggregate quarries in the western and south-western US.
Santa Fe will get gold mines in Nevada and California and rights to several exploration sites.
The Santa Fe companies made pre-tax profits of about dollars 53m ( pounds 35m) in 1991, with tangible net assets of about dollars 131m. Gold Fields Mining's tangible assets are valued at dollars 150m, and the company made pre-tax profits of dollars 52m on turnover of dollars 189m in the year to last October.
The coal assets will be managed by Hanson's Peabody company, which already has 8 billion tons of reserves.
Analysts said the Santa Fe reserves were low-sulphur coal, which is more valuable because it is less polluting, whereas a lot of the Peabody reserves have higher sulphur contents.
The deal has still to be approved by US regulators, who may ask questions about the tax-free status of the deal.
Martin Taylor, Hanson's deputy chairman, said he did not expect the deal to have significant financial implications for the group.
'We are the largest producer of coal in the United States and this deal strengthens our hand,' he said.
He dismissed concerns that carbon tax legislation in the US might hit the group's coal interests. 'Coal is used to produce more electricity in the US than any other fuel and further taxes will just make the price rise.'
Earlier, at Hanson's annual meeting in London, Lord Hanson, the chairman, would not comment on the company's interest in bidding for British Coal assets.
Questioned by shareholders, he said: 'We believe that coal has a great future.'
He said it would be inappropriate to comment on British Coal until the Government had decided what its plans were.
However, in reply to another question he said that a large acquisition of 'a new principal business is something we would like to do'.
Lord White, 70, who runs the US half of the Hanson empire, was unable to attend the meeting because of illness.
Hanson shares rose 6 1/2p to 243 1/2p.