Curling stone
“The Scots in particular believe that the best quality curling stones are made from a specific type of granite called ‘Ailsite’, found on the Ailsa Craig, an island off the Ayrshire coast. Most curling stones are made from this granite. Because of the particular rarity of Ailsite, costs for curling stones can reach as much as $1500 (USD) for Olympic grade stones. Many curling clubs use a lower grade stone that can be upwards of $500. Very informal neighbourhood curling clubs with limited resources may make cylindrical ‘curling stones’ out of concrete-filled cans.” Curling, Wikipedia
