BBC News
By Rebecca Morelle
Bumping around in the back of a truck, we descend underground.
Just the headlights guide our way into the gloomy tunnels ahead.
We’re heading into South Crofty mine in Cornwall, where copper and tin have been excavated for hundreds of years.
"This tunnel, we believe, is Elizabethan, so it dates back to the 1500s,” says Richard Williams, CEO of Cornish Metals, as we enter one of the oldest parts of the site.
But access is limited. Much of the mine flooded after South Crofty shut in 1998.
image captionCornish Metals wants to open up South Crofty again