what are curling stones made of

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.