Olympic Geology

The curling stone is made of granite and is between 17 and 20 kg.

The granite for the stones comes from two sources: Ailsa Craig, an island off the Ayrshire coast of Scotland, and the Trefor Granite Quarry in Wales.

Ailsa Craig, off the SW coast of Scotland

Ailsa Craig is the traditional source and produces two types of granite, Blue Hone and Ailsa Craig Common Green. Blue Hone has very low water absorption, which prevents the action of repeatedly freezing water from eroding the stone. Ailsa Craig Common Green is a lesser quality granite than Blue Hone. In the past, most curling stones were made from Blue Hone but the island is now a wildlife reserve and the quarry is restricted by environmental conditions that exclude blasting. The last "harvest" of Ailsa Craig granite took place in 2013, after a hiatus of 11 years; 2,000 tons were harvested, sufficient to fill anticipated orders through at least 2020.

Trefor granite comes from the Yr Eifl or Trefor Granite Quarry on the north coast of the Llŷn Peninsula in Gwynedd, Wales.