POTASH - is not potassium permanganate
The Boulby Potash Mine
The Boulby potash mine, situated on the North Yorkshire coast, is the UK's only commercial potash mine and the most important non-hydrocarbon mineral operation in Britain. The mine started production in 1973 and is currently managed by Cleveland Potash Ltd and employs over 800 workers. Mining operations cover some 13.5 km, reaching approximately 5 km offshore and The Crown Estate is responsible for the deposits of potash occurring beneath the seabed. We issue a lease for its extraction and each year we receive revenue based on the amount of potash extracted from the offshore section of the mine.
Potash is a generic term for a variety of potassium bearing minerals but it is Sylvinite that is primarily mined in the UK. Sylvinite is a mixture of potassium chloride and salt in varying proportions and at Boulby it runs in seams averaging 7m in thickness at depths of up to 1,500m. About 90% of UK potash is used in the production of fertiliser while the remaining 10% is used in the chemical and pharmaceutical industries. However around 60% of all UK production is exported to the continent each year.
taken from:
http://www.thecrownestate.co.uk/minerals_potash