Ailsa Craig

Ailsa Craig (; ; ) is an island of in the outer Firth of Clyde, west of mainland Scotland, upon which microgranite has long been quarried to make curling stones. The now-uninhabited island comprises the remains of a magmatic pluton formed during the same period of igneous activity as magmatic rocks on the nearby Isle of Arran.

The island, colloquially known as "Paddy's Milestone", was a haven for Catholics during the Scottish Reformation in the 16th century, but is today a bird sanctuary, providing a home for huge numbers of gannets and an increasing number of puffins. Provided by Wikipedia