Valentia Slate Quarry in Kerry, is to provide slate for renovation work in the Palace of Westminster.
The slate was used in the original building and also to roof the palace when it was rebuilt after a fire in 1834.
The slate is laid in ornate designs on the floors of the building, which are being restored.
Slate from the quarries, first opened almost 200 years ago, can be found as far away as Brazil, in St Paul’s Cathedral, and in railway stations in Nottingham, Derby, Rugby, and Leicester.
Vast amounts of the slate was also used for shelving in the Public Records Office in London.
The quarries — where six people are currently employed — closed in 1911 and were reopened by a consortium of local businessmen in 1999.
One of those, Micheal Lyne, told the Irish Examiner the latest contract helps to consolidate the success of the venture.
“As well as being a prestigious contract, it is also an endorsement of the quality of Valentia slate. It’s a great boost to get a job like this in difficult economic times,” he said.
“We had been on a three-day week, but we’re going back full-time and the contract will mean a few months’ work each year.”
Old links with Westminster were restored in 2004 when Mr Lyne approached the authorities there, after learning that renovation works were being planned.
Conservation architects expressed an interest in doing business and the quarries obtained a contract for the years 2004 to 2007.
Another contract was signed for 2010 and now comes a new five-year contract.
Renowned for its durability and beauty, the slate also has several other uses, including hearthstones, gravestones, counter tops, floor tiles, furniture, and wall capping.
“It’s a very hard substance. Unlike other stone, it stays clean and nothing grows on it. There are gravestones in Valentia since the 1820s and the lettering is still perfectly clear on them,” said Mr Lyne.
Meanwhile, the slate could be in over 4,000 Irish schools within three years if a project to commemorate the Easter Rising is successful.
The company plans to have the 1916 proclamation engraved on slabs of slate for display in schools countrywide.