"There's potash in them thar hills" might lack the potency of the Klondike's rallying cry, but the discovery is causing passions to run high in the North York Moors. Deep beneath the protected national park landscape between the tourist towns of Whitby and Scarborough resides the world's largest deposit of agricultural fertilizer.
The estimated 1.3 billion tonne treasure trove could help solve the globe's emerging food crisis.
But getting it out of the ground is no easy matter. Laid down nearly a mile underground by the evaporation of a Permian-age sea stretching from England to Poland 250 million years ago, the polyhalite from which potash is processed is inconveniently situated in one of Britain's best-loved and fiercely guarded environments.
International mining conglomerate Sirius Minerals is keen to exploit the reserves over the next 50 years and meet the burgeoning demand for the high-quality mineral currently fetching around $500 a tonne on world markets, but many locals are vehemently opposed.
Critics complain that the plans represent the greatest intrusion into a National Park since the creation of Sir Basil Spence's Trawsfynnyd nuclear power station in the heart of Snowdonia half a century ago. To supporters, the scheme it is an opportunity to help reverse the North East's long history of industrial decline, provide up to 4,000 local jobs and bring millions of pounds to an area struggling in the face of recession.
Bumping along a forestry track down towards May Beck, a beauty spot popular with coast-to-coast walkers, bikers and picnicking families, the low rumble of an exploratory rig can be heard.
It is one of 13 given the go-ahead by the National Park Authority under its obligation to help chart the nation's strategic supplies of minerals. Rising high above the fir tree plantations that surround it, drilling has been going on round the clock as local Sirius subsidiary York Potash seeks to establish exactly how they will remove their prize, which stretches east beyond the hills out under the North Sea.
It has yet to submit a planning application for a fully operational mine, but Tom Chadwick, a retired art teacher and chairman of the North Yorkshire Moors Association, says opposition is swelling. "What is the point of having national park designation if you are going to do this? We are completely opposed to an industrial development on this scale. The company has had a very well-organised publicity machine and people have the idea that it is a done deal and that nothing will stop it. But it is nothing of the kind and we have a growing number of concerned people joining our ranks," he says.
No one knows yet whether the planned mine will receive the consent of the five planning authorities who must agree to the proposal – due to be finalised later this year – without it being called in for a delaying and expensive public inquiry. In the meantime Mr Chadwick has more immediate concerns, in particular the vast volume of spoil created by the drilling process, a pile of rock and sludge he estimat es at up to 700,000 cubic metres. "This will cover a football field to a height of 400ft. There is no possibility you can hide it. The company has not said what they intend to do with it. You either have to create an artificial landscape or find some other solution which won't create the kind of visual intrusion you don't want to see," he says. The company is also proposing to create a 40km pipeline taking the polyhalite in solution to a new refinery it is planning on Teesside – an area desperate for jobs.
"The economic argument is a very powerful one; we are fully aware of that," he concedes. "But there has been a huge exaggeration in the number of jobs that might emerge from this and there is no guarantee those jobs will go to local people."
Yet the history of the North York Moors is inextricably linked to mining. The remnants of ancient ironstone works scar the local landscape and the industry helped turn forgotten backwaters such as Rosedale into Victorian boom towns with the arrival of the railway. Today tourism is the biggest employer – the only comparable source of jobs is another potash refinery built within the national park 40 years ago in the face of opposition, which looms large above the popular holiday village of Staithes further up the Cleveland coast at Boulby.
Gareth Edmunds of York Potash said there is considerable local support for the project and claims to have the backing of councils and the local MP and he hopes work can get underway next year. As well as being of national and global importance, he says, it will bring much-needed jobs. The company is also proposing a community fund for projects and bursaries which could be worth up to £9m a year.
"Yes, if we could build this somewhere else it would be much easier. But we can only extract the mineral from where it exists," he says. "But we are happy that we are doing everything we can to minimise the visual intrusion. We are not here to cause damage or create unnecessary disruption."