Cornwall could soon be supplying key metals used in our smartphones and electric cars as part of a multimillion pound rejuvenation of the county's mining industry.

A team of geologists is planning to start mining for lithium - a key component in batteries - contained in hot springs deep under the Cornish countryside.

Some estimates report that global demand for lithium could triple by 2025. The metal is key to the booming production of electric vehicles, power storage and lithium-iron batteries.

Meanwhile Cornwall's largest tin mine - which closed 20 years ago - is also planning to re-open due to rising demand for the metal.

Cornish Lithium has more than 300 square kilometres (186 square miles) of exploration rights across Cornwall and hopes to start testing samples for lithium later this year.


Image: Lithium was first detected in Cornwall 150 years ago but back then there was no use for it

Lucy Crane, a geologist from Cornish Lithium, told Sky News the metal was first detected 150 years ago, but back then there was no use for it.

She said: "They took a sample of it in 1864 and Professor Miller from Kings College London did some geological analysis on it and found that actually it was unusually rich in lithium.

"He wrote a paper on it in which he said 'this could basically be a potential source of lithium in the hot springs in the mines, if only there was a use for it'."

There are potentially huge reserves of lithium under the countryside.

Ms Crane added: "We want to put water bore holes in from the surface to intercept geological structures at depth and pump the fluids back to the surface.

Image: A mining revival in Cornwall is possible because the county's resources are commercially viable again

"It's at the top that it will enter a processing plant where we'll directly extract the lithium from those fluids. We really think the southwest is prospective as a source of lithium."

Cornish Lithium says their method of extracting lithium from water means the environmental impact is minimal and does not require large mines.

As well as lithium mining, the last tin mine in the UK to close is set to re-open.

South Crofty mine in the village of Pool was closed in 1998 because of falling tin prices and a lack of investment.

But tin prices are now four times what they were then and the metal's use in high-tech, such as phone and tablet touch screens, means demand is rapidly growing.

Image: Strongbow Exploration boss Richard Williams says demand is nearly overtaking supply

Canadian mining firm Strongbow Exploration is investing millions of pounds into re-opening the mine.

The company's chief executive, Richard Williams, said demand is close to overtaking supply.

He said: "What we are seeing is a lot of research into what we call the high-tech world.

"That includes renewable power, power generation, solar panels, electric vehicles and lithium ion batteries - and the application of tin in some of those."

It is understood there could potentially be 150,000 tonnes of high-grade tin still untouched in the South Crofty mine.

Image: The demand for metals and minerals is growing worldwide

Professor Kip Jeffrey from the Camborne School of Mines says a mining revival in Cornwall is possible because the county's resources are commercially viable again.

He said: "There's always been a romantic view of how it would be great to start mining up again, but there's a reality behind that now.

"Some of the minerals that weren't necessarily the ones that were worked previously have suddenly become much more in demand. So those mines are now seen as competitive on a global scale."