rock salt sample

The Production of Salt in Ancient Ireland

An adult needs less than 6g of salt per day, but it is still a requirement for survival. Without sodium, the main component of modern table salt, the human body is at risk of heart failure and an increased risk of death. But how did people guarantee an intake of salt in ancient Ireland?

As you season your dinner this evening, spare a thought for those ancient Irish communities who couldn’t ride their horse down to the local store and pick up a shaker of Saxa. They could, however, trade other goods for sacks of mined salt.

Salt in Ancient Ireland

Rock salt deposits
Rock salt deposits are left behind when salt water evaporates.

Natural salts were in abundant supply for those ancient Irish societies, and man was able to sustain his salt intake from eating wild game. But during the winter months (of which Ireland is famous) game was less active, and preserving food became essential.

Before the introduction of salt mining, salt pans – low-level areas were saltwater gets trapped and, over time, the water evaporates or is made to evaporate, leaving salt deposits behind – were dotted around the Irish coast.

Conall Corc and the Corco Luigde, written in the eighth century, documents a tribute of salt paid by the Aran Islands to the King of Cashel. Salt, it seems, was in great demand.

When the Celtic settlers came with their knowledge of mining – copper and iron ore, for example – it is generally accepted that they began mining salt, too.

Though there is little evidence of extensive salt mining in ancient Ireland, one of the only known salt mining locations in Ireland is that of Kilroot, Carrickfergus, in County Antrim. Modern records suggest its current mining operation has existed since 1965, but the site itself is estimated to be over 200 million years old.

The Kilroot salt mine was formed in the Triassic period, most likely by a body of salt water that got landlocked and, as temperatures rose, the water evaporated, leaving a wealth of raw salt deposits behind.

Today, the mine excavates 500,000 tonnes of rock salt a year, and it is used in winter road gritting across Ireland, the United Kingdom, and even the United States.

Whether the mine was used by the ancient Irish or not, we cannot say for certain. But it was rediscovered in the early 1850s when the Marquis of Downshire was searching the local area for coal deposits. Shafts were drilled and water was pumped down below the 600ft of rock and sediment, and a brine mixture was brought up for evaporation.

Salt was essential for winter stores in ancient times. It was used as a preservative for meat that would last the cold months. Beef, pork, fish – anything that could go off would if it had not been salted.

Beyond food preservation, salt was also used by the druids in their rituals. A bowl of salt would be placed beside a man’s deathbed, perhaps to give an offering to Manannán mac Lir on his way to Tír na nÓg.

In any event, salt has been a mainstay of the Irish ways of life for longer than we know.

Cover photo courtesy of Lech Darski
Peter J Merrigan
Peter J Merrigan was first published at the age of 17 in the Simon & Schuster anthology, Children of the Troubles. He has studied extensively and maintains a passion for pre-Christian Ireland. He is the author of the Ailigh Wars Saga novels, set in Iron Age Ireland.