The quirky geology behind Olympic curling stones

[Buttoneer]

Last edited Mon Feb 16, 2026, 10:02 AM - Edit history (1)

https://www.scientificamerican.com/article/the-quirky-geology-behind-olympic-curling-stones/

The rocks used in the Olympic sport of curling come from one island in Scotland and one quarry in Wales. What makes them so special?

Each place has two types of rock used for curling stones: Ailsa Craig common green and Ailsa Craig blue hone, and blue Trefor and red Trefor. All four types are granitoids, which are igneous rocks, meaning they form as magma or lava cools and crystalizes. Ailsa Craig’s rocks formed around 60 million years ago when magma pushed into a relatively shallow layer of the Earth’s crust during the rifting that formed the Atlantic Ocean. Trefor’s formed around 400 to 500 million years ago during a mountain-building event called the Caledonian Orogeny. Both are, geologically speaking, fairly young. “Having a young rock is probably a good thing because it means that it's less likely to have incurred stresses related to different tectonic events” before it is subjected to the stresses of curling, Leung says.

Common wisdom has held that rocks from these two sources were ideal because they contained very little quartz, a brittle, silica-based mineral that would be less than ideal for expensive stones constantly knocking into each other. (Curling stones cost around $600 a pop, and they’re typically used for 50 to 70 years.) But Leung found that in fact all four rocks contain quartz. Yet under the microscope, “I found almost no fractures,” he says, likely because of their young age.

[niyad]

1. You are allowed to quote four paragraphs.

[Buttoneer]

2. Thanks! I added more info to the op

[niyad]

3. Thank you. That was fascinating. The things one learns on DU!

[Spazito]

4. Interesting!

Thanks for this.

[ProudMNDemocrat]

5. I was first introduced to Curling in 1974.

When my husband and I transferred to a town 8 miles south of the Canada border in NE North Dakota, we went to watch a Curling match.

My husband had no idea what this sport was. I told him it was Bocce Ball, but on ice instead of grass. He understood being he was half Sicilian. His uncles and cousins played it in parks and their small back yards in Brooklyn and the Bronx.