Speaking of the Olympics, I thought this was interesting:
Curling stones are specialized 38–44 lb (average 42 lb) granite rocks, exclusively sourced from Ailsa Craig, Scotland, or Trefor, Wales, known for low water absorption to prevent freezing damage. Used in sets of 16 (8 red, 8 yellow handles), they cost over $600 each or ~$9,600 per set. With proper maintenance—refurbishing the running band every 5–10 years—they can last for decades.