Every curling stone used in the 2026 Winter Olympics comes from granite quarried on Ailsa Craig, a small uninhabited island off Scotland's coast. This unique material ensures durability and precise movement on the ice, as highlighted by Team USA's recent silver medal in mixed doubles curling. The stones' exceptional properties have made them the standard since the sport's Olympic debut in 1924.
Team USA secured silver in mixed doubles curling at the 2026 Winter Olympics, marking their first appearance in the event's final. In the semifinal against Italy on Monday, American curler Cory Thiesse delivered the decisive shot, knocking the Italian stone from its position to advance.
Curling stones must weigh between 38 and 44 pounds (17 and 20 kilograms) and are designed to endure decades of use. Kays of Scotland, which has crafted stones since 1851, supplied all 132 stones for these Games, certified by the International Olympic Committee. Each stone costs over $960, with a full set of 16 exceeding $15,000. Since 2006, Kays has exclusively provided stones for the Winter Olympics, using granite solely from Ailsa Craig.
This granite's fine-grained structure binds minerals tightly, offering resilience against collisions and a smooth polish for gliding on pebbled ice. Its unique composition enables an intrinsic curl in trajectory and consistent bounce upon impact. Three granite types exist on the island: common green for the stone's body and striking band, which features black mineral specks for springiness; and blue hone for the concave running band, prized for low porosity that maintains texture over time.
The island's rock, formed 60 million years ago, has unusually low aluminum content, yielding rare minerals like arfvedsonite, aegirine, and aenigmatite. "It’s not just about the ability to withstand chips and cracks. It also has to do with how it moves on the ice and how the stones bounce when they hit each other," said Dr. Bob Gooday, a geological analyst at National Museums Scotland.
Curling originated in 16th-century Scotland, debuting as an Olympic medal sport in 1924 at Chamonix, France. The Royal Caledonian Curling Club has mandated Ailsa Craig granite since 1838, standardizing its use in competitions. Mark Callan, World Curling's chief ice technician and former Kays director, noted the company produces 2,000 to 2,500 stones annually for 77 countries. Alternatives, such as ceramics, fail to replicate the granite's consistent curling behavior, as explained by Dr. Derek Leung, a mineralogy professor and curler. "There is consensus that Ailsa Craig stones are the best," added Dr. Matthew McDowell of the University of Edinburgh.
