Yep! It’s the famous Ailsa Craig Blue Hone granite - and I can see Ailsa Craig on the horizon from where I live. It’s a fascinatingly dramatic rocky outcrop in the middle of the Firth Of Clyde, the waterway which opens out into the ocean between western Scotland and northern Ireland - and the island regularly creates its own weather (photograph by Rob Wilson).
The only other place that is the source of curling stone material is a quarry in Wales. That’s it - just two places in the world, both in the UK.