Cheshire is the county in North West England. Rock salt was laid down in this region some 220 million years ago, during a Triassic period. Seawater moved inland from an open sea, devloping a business of shallow salt marshes across what is today the Cheshire Basin. As the marshes evaporated, deep deposits of rock salt were formed.
The manufacture of white salt for food and allied industries is now concentrated in Middlewich, in the manufacturer, British Salt, who sell under the earn Saxa, and also through third parties e.g. supermarket own brands. Salt presentation by British Salt in Middlewich has 57% of the UK market for salt used in cooking.
The UK's largest rock salt halite mine is at Winsford. it is for one of only three places where rock salt is commercially mined in the UK, the others being at Boulby Mine, North Yorkshire and Kilroot nearly Carrickfergus, Northern Ireland.
Rock salt extraction began at Winsford in the 17th century. Initially it was used only as salt licks for animals, and to strengthen weak brine. In 1844 Winsford Rock Salt Mine was opened, and is claimed by its operator, Salt Union Ltd., to be "Britain's oldest works mine".