The potassium compound is used in fertilisers and the UK's only current mine is at Boulby in North Yorkshire.

BBC: Sirius Minerals wins RGF cash for geosciences centre

Sirius Minerals claims some of the world's best deposits of potash, a potassium compound, lie beneath the North York Moors National Park.

BBC: Sirius propose North Yorks pipeline to transport potash

Potash is a potassium compound mostly used in fertilisers.

BBC: Company puts ?54m into North Yorkshire potash scheme

Potash is a potassium compound mainly used in fertilisers.

BBC: Artist's impression of mine buildings site