Ailsa Craig Curling Stones

Curling stones are not "made from Ailsa Craig granite" in some vague, interchangeable sense — nor is Ailsa Craig the only place curling-stone granite has ever come from (Trefor granite in Wales has also been used). What is true, and remarkable, is narrower and more precise: for over a century, one family-owned firm has held exclusive rights to quarry two specific granite types from one small, uninhabited island, and that firm has supplied the stones for every Winter Olympics curling competition bar one since 1924.

This card distinguishes between documented facts — the corporate history of Kays of Scotland, the dual-granite specification, and the company's role as official Olympic/World Curling Federation supplier, all confirmed by institutional and press sources — and actively-researched science, where the precise mechanism explaining the granite's remarkable resistance to fracturing is still being refined by geologists, with the leading current explanation (geological youth, hence low residual stress) presented as the best available account rather than settled consensus. There is no significant legend-myth tier to correct here beyond the loose popular assumption that "all curling stones" universally come from Ailsa Craig; in fact Kays supplies the stones used in official competition and the Olympics specifically, while other manufacturers have historically used other quarries (notably Trefor granite in North Wales) for lower-tier or recreational stones.

The Island and Its Rock

Ailsa Craig — a 99-hectare granite plug rising sharply from the Firth of Clyde, about 16 kilometres off the Ayrshire coast — is covered in detail as a landform and wildlife site on its own "Locations & Landmarks" card. This card concerns a narrower and, in its way, odder story: how a single uninhabited island came to dominate the manufacture of a specific piece of sporting equipment used at the highest level of a Winter Olympic sport. The island's granite formed roughly 60 million years ago as magma intruded and cooled during the tectonic rifting that opened the North Atlantic Ocean. That relative geological youth turns out to matter: unlike older granites that have absorbed millions of years of tectonic stress and consequently carry networks of microscopic fractures, Ailsa Craig's granite is comparatively free of these internal flaws. Curling stones endure enormous repeated impact as they strike one another on the ice, and granite riddled with fine cracks is prone to chipping or shattering. Ailsa Craig granite, by contrast, has proven able to withstand decades of use with minimal damage — a property long known empirically by curlers and quarrymen, and more recently investigated scientifically by geologists seeking to explain exactly why.

Two Granites, One Stone

A finished curling stone is not a single uniform lump of rock but a composite of two distinct granites quarried from different parts of the island, each doing a different mechanical job. The bulk of the stone — its body, where it is struck by other stones in play — is cut from Common Green granite, sometimes marketed under the proprietary name "Ailsite." This rock has a comparatively coarse and variable grain structure, a property that, counterintuitively, helps it absorb and disperse the energy of collisions without chipping or cracking at the point of impact. The stone's running surface — the narrow concave ring of rock that actually contacts the ice — is a separate insert of Blue Hone granite, fitted into the base of the stone (these inserts are sometimes called "Ailserts"). Blue Hone has a much finer, more uniform grain and is markedly less porous than Common Green. Porosity matters acutely here: a curling stone that absorbs water into its running surface and is then exposed to freezing temperatures can suffer the rock equivalent of frost damage, with trapped moisture expanding and causing fractures. Blue Hone's low water absorption makes it resistant to this failure mode, which is why manufacturers reserve it specifically for the ice-contact ring rather than using it (or Common Green) throughout. It is worth noting, against an older folk explanation, that modern geological analysis has found that all the granite varieties historically used for curling stones — not just the supposedly "purer" Ailsa Craig rock — contain measurable quartz; the resistance to fracturing is now attributed less to an absence of quartz than to the comparative youth and low pre-existing stress of the Ailsa Craig granite body specifically.

Kays of Scotland and the Quarrying Monopoly

The firm that turns this raw granite into finished stones is Andrew Kay & Company, trading as Kays of Scotland, founded in 1851 by William Kay and his sons Andrew and Thomas in Haugh, East Ayrshire, and operating today from a workshop in Mauchline. Early in the company's history, the Kay family secured permission from the family owning Ailsa Craig to harvest its granite — an arrangement that, over generations, hardened into an effective exclusivity that persists to this day. Ownership of the firm itself passed down a family line to James Wyllie, brother-in-law of founder Thomas Kay, and the business has remained wholly owned by the Wyllie family since, with a descendant, James "Jimmy" Wyllie, at its head as of the 2020s. This is not a large-scale industrial operation: as of the mid-2020s, the Mauchline workshop employs around six craftsmen and produces roughly 1,800 to 2,000 stones a year, with each stone taking around six hours of shaping, fitting, and polishing (using pumice and diamond pads) to complete, and weighing approximately 18 kilograms when finished.

Access, Conservation, and Supply Constraints

Ailsa Craig today is uninhabited and managed principally as a wildlife reserve — notably for its large gannet colony — and blasting or large-scale quarrying on the island is now prohibited under its conservation status. This has turned what was once a straightforward extraction business into something closer to a stockpiling operation: rather than continuously quarrying, Kays periodically negotiates and executes large one-off granite collections intended to supply production for years or decades at a time. A collection of around 1,500 tonnes was taken in 2002, and a further collection of around 2,000 tonnes — expected to yield in the region of 10,000 finished stones — was taken in 2013. These finite stockpiles, set against the island's protected status, mean that the long-term future of genuinely Ailsa Craig-sourced curling stones is a live supply question for the sport, even as demand (driven substantially by curling's growth in markets such as Canada, now the company's largest market) continues to grow.

Olympic and Competitive Status

Kays of Scotland has supplied the stones for every Winter Olympic Games curling competition since curling's first Olympic appearance in 1924, with the sole modern exception of the 2002 Salt Lake City Games. The company describes itself as the sole supplier of competition stones to the World Curling Federation, meaning that essentially all top-level international curling, Olympic and otherwise, is played with stones quarried from this one island. For the 2026 Milano Cortina Winter Olympics, the stones in use are specified as Ailsa Craig Common Green granite bodies fitted with Blue Hone running surfaces, continuing a supply relationship now running for more than a century.

• A single finished curling stone is a composite of at least two different granites from two different parts of the same island — it is not cut from one uniform block.
• Despite popular belief that the rock's purity comes from an absence of quartz, modern analysis has found quartz present in all the historical curling-stone granite varieties, Ailsa Craig included.
• Ailsa Craig's granite is geologically young by granite standards — formed around 60 million years ago — and this relative youth, not an absence of minerals, is the leading current explanation for its resistance to cracking.
• Kays of Scotland is a genuinely small operation: as of the mid-2020s, around six craftsmen in a single Mauchline workshop produce the stones used across the entire elite global sport of curling.
• Because Ailsa Craig is now a protected bird sanctuary where blasting is banned, the company works from large periodic stockpiles (one collection alone, in 2013, was expected to yield around 10,000 stones) rather than ongoing quarrying.
• Salt Lake City 2002 stands out as the single Winter Olympics since 1924 not supplied by Kays of Scotland.
• A finished Olympic-grade curling stone retails in the region of £750 (roughly $1,030 as of 2026), reflecting both the scarcity of the raw material and the roughly six hours of skilled craftsmanship per stone.
• Ownership of Kays of Scotland has stayed within one extended family — from the founding Kays to the Wyllies who inherited the business by marriage — for well over 150 years.

• Do not state that all curling stones everywhere are made from Ailsa Craig granite. Correct phrasing: Ailsa Craig granite, via Kays of Scotland, supplies the stones used in elite and Olympic competition; other quarries (e.g., Trefor granite in Wales) have supplied stones historically and for other tiers of the sport.
• Do not state that curling-stone granite from Ailsa Craig is uniquely "quartz-free," as older folk explanations sometimes claim. Correct phrasing: analysis has found quartz present in all curling-stone granite varieties studied; the durability of Ailsa Craig granite is better attributed to its relative geological youth and low residual internal stress.
• Do not state an exact, single, documented date for "the first" extraction of curling-stone granite from Ailsa Craig. Correct phrasing: sourcing is traditionally dated to the early 19th century, without a single precisely documented first instance in the sources consulted.
• Do not imply Ailsa Craig granite supply is limitless or that quarrying continues freely today. Correct phrasing: blasting is now prohibited under the island's wildlife-reserve status, and Kays works from periodic large stockpiled collections (e.g., 2002, 2013) rather than ongoing extraction.