Scottish island source for granite used in Winter Olympic sport curling

An uninhabited island 10 miles off off South Ayrshire, Scotland,

is the source of the super-dense granite used to make curling stones for the Winter Olympics.

Jim English, co-owner of Kays Curling, takes a few seconds to evaluate a boulder during a recent visit. He's assessing it for big cracks and large specks on the surface.

"It's not just a case of landing a boat and then looking for granite. There's a particular type of granite we're looking for. We look for ones that have got really tight surface pattern."

The common green granite comprising the body of the stone is found on the southern end, and the blue hone granite that forms the running surface is on the other side of the island.