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

The UK's only current mine is at Boulby in North Yorkshire.

BBC: Share plan to raise ?50m for North Yorkshire potash scheme

As well as funding the development of the Boulby site, the investment will go towards upgrading the company's Teesport operation near Middlesbrough, which exports potash mined at Boulby.

BBC: Cleveland Potash Boulby development to create 270 jobs