The metal yet to be extracted at a tin mine in Cornwall has been valued at $2.4bn (£1.5bn).
Celeste Copper Corporation (CCC), which hopes to start re-mining South Crofty, made the estimation in a report.
An independent mining expert made the valuation by comparing the quantity of tin believed to be in the mine, about 7.95m tonnes, with current markets.
CCC also said it planned to spend £7.8m in the next 12 months on making the site ready for mining.
The work CCC is planning to carry out during 2013 includes spending £1.1m on drilling at the site and £2.6m on starting to pump water out of the flooded mine.
Flooded mine workings
The Canadian-owned company, which has a number of US investors, will focus on pumping out shallow old workings in the Dolcoath area.
The company has said it is mainly interested in mining in areas of rock between existing flooded mine workings, but some of those flooded areas need to be pumped for safety.
So far the scheme has attracted investment of about £15m in the past ten years, but up to £75m will be needed to make it operational.
It is hoped the work taking place in 2013 will lead to more companies wanting to invest.
South Crofty originally closed in 1998 after the price of tin hit an all time low, a decrease which started in 1985.
For the past six years the price of tin has been rising.
CCC has said it wants to extract tin and other metals including zinc and copper, at the mine with the hope of creating at least 220 jobs.