What do you think of this fact?
The curling stones gliding across the ice at the Winter Olympics share the same home address: Ailsa Craig, a lump of rock in the Firth of Clyde off Scotland’s west coast. Nobody lives there. The seabirds don’t count.
A volcanic plug full of perfect granite
According to World Curling, Ailsa Craig is a volcanic plug that formed about 60 million years ago. Team GB puts the island at about 0.75 by 0.5 miles, rising to 340 meters. Humans were active there between the 16th and 19th centuries, but today the island belongs to the birds: it is home to Scotland’s third largest gannet colony, and puffins drop by too.
The rock comes in two kinds of granite. Ailsa Craig Blue Hone is extremely water-resistant and is used for the running edge, the part that actually touches the ice. Ailsa Craig Common Green makes up the rest of the stone, because it takes hits without splintering when stones crash into each other.
One company, one island
Only one company may take granite from the island: Kays of Scotland, based in Mauchline, Ayrshire. It holds the exclusive rights, granted by the Marquess of Ailsa. Kays was founded in 1851, and according to World Curling, Olympic stones have been hand-crafted in Scotland since 1998.
Nobody is digging there every day. Team GB says the granite is harvested roughly once a decade, most recently in 2020. World Curling adds that crews used to blast the rock, but there is now so much fallen granite lying around that dynamite isn’t needed anymore.
For the Olympic and Paralympic Games in Milano Cortina 2026, Kays made 132 new stones by hand. According to Team GB, an Olympic-level stone typically weighs 20 kilograms.
Bonus fact: Ailsa Craig isn’t the only source of curling granite. Team GB says a quarry in Trefor in North Wales supplies granite for curling stones as well.
All that sweeping and shouting on the ice comes down to a rock from an island where only seabirds live.