Curling stones (also called rocks) are made from very tough, low‑absorption granite specifically chosen so it won’t chip or wear down on ice.

Main materials

  • Modern curling stones are made almost entirely of special granite, not concrete or metal.
  • This granite comes from just a few places in the world, mainly:
    • Ailsa Craig, a small island off the coast of Scotland (Blue Hone and Ailsa Craig Common Green granites).
* Trefor quarry in Wales (Trefor granite).

Why this granite?

  • The granite used has very low water absorption, so repeated freezing and melting of water on the ice does not crack or erode the stone.
  • It is extremely hard and durable, which helps the stone keep its shape and polished running surface through thousands of slides and impacts.

How a stone is built

  • A typical Olympic‑level stone has:
    • A main body made from Ailsa Craig Common Green granite.
* A running band (the thin ring that actually contacts the ice) made from Blue Hone granite, which is especially resistant to cracking and moisture.
  • Finished stones weigh about 38–44 lb (17.24–19.96 kg), with a maximum circumference of 36 in and at least 4.5 in height.

TL;DR: When people ask “what are curling stones made of,” the precise answer is: specialized, low‑absorption granite from just a couple of quarries in Scotland and Wales, carefully shaped so only a narrow granite band touches the ice.

Information gathered from public forums or data available on the internet and portrayed here.