U.S. fans’ interest in curling has grown from curiosity to full-blown interest during the 2026 Winter Olympics, with the mixed doubles team of Cory Thiesse and Korey Dropkin winning silver on Tuesday and the women’s curling team beating Canada in a round-robin tournament in Cortina on Friday.
Much of curling’s appeal may come from its differences from other winter sports such as skiing, skating, snowboarding and hockey. Why does the playing surface (called the sheet) look like a giant shuffleboard court? Why do players sweep the ice? What are those big rocks that slide along the rink toward the target (or “house”)?
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Stone! These big, heavy Frisbees — weighing between 38 and 44 pounds — fans don’t typically find in sporting goods stores or in the aisles next to basketballs at Walmart. At least not a professional, competition-grade curling stone. The curling stones used in the Olympics are made in a small town factory by a company called Kays Scotland, which handcrafts stones for professional competitions and the Olympics.
Olympic and professional grade curling stones are produced in only one location: Ailsa Craig, an island off the coast of Scotland where the common green and blue granite is found. (AP Photo/Alastair Grant)
(Associated Press)
But the source of the granite used to make these stones is found in only one place, an uninhabited island called Ailsa Craig 10 miles off the country’s coast. The island, also known as Paddy’s Milestone, was formed by a volcano 60 million years ago and is composed of dense granite, the material from which curling stones are made.
The remote island where the curling stones are made sounds like a folk tale or myth. But it’s true. The Ailsa Craig is composed of “microgranite” — formed from rapidly cooling magma, The Athletic reports — which makes the stone ideal for sliding on the ice and remaining intact when colliding with other stones during play.
Jim English, managing director of Case Curling, inspects a granite boulder on Elsa Craig Island off the coast of Scotland in November 2025. (AP Photo/Alastair Grant)
(Associated Press)
The island’s Blue Hone Granite, Common Green Granite and Red Hone Granite are distinct from other granites seen and used around the world. According to NASA, the rock has a tight molecular structure that makes it water-resistant and crack-resistant. This tight texture also helps the granite withstand polishing and “curl” as it slides along the ice.
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Until 2050, Kays Scotland has exclusive rights to the Blue Hone quarry, which is very water-resistant, and the Common Green quarry, which is less susceptible to collision with other rocks in freezing temperatures. The company, based in Mawlyn, has been producing curling stones from granite for 175 years.
Unsurprisingly, the growing popularity of curling since it became an official Olympic sport in 1998 has necessitated the extraction of more granite from Ailsa Craig.
Case Scotland initially mined 210 tonnes of rock, enough to produce at least 1,000 curling stones. By 2013, the company had harvested 2,500 tons of Common Green and 500 tons of Blue Hone, The Athletic reports. According to Case operations manager Ricky English, this is equivalent to taking “a teaspoon” out of an ice cream tub during the period of its available supply agreement.
