What is the name of a Scottish island where granite to make curling stones is quarried?

Curling is a sport in which players slide stones on a sheet of ice toward a target area which is segmented into four concentric circles.

The curling stone is made of granite and is specified by the World Curling Federation, which requires a weight between 38 and 44 pounds (17.24 and 19.96 kg)

The granite for the stones comes from two sources: Ailsa Craig, an island off the Ayrshire coast of Scotland, and the Trefor Granite Quarry in Wales.

Kays of Scotland (the only remaining UK manufacturer and supplier of curling stones) has been making curling stones in Mauchline, Ayrshire, since 1851 and has the exclusive rights to the Ailsa Craig granite, granted by the Marquess of Ailsa, whose family has owned the island since 1560.