Copper

Copper has very high heat conductivity, which means it conducts heat quickly. For this reason, copper is used in cooking sugar, where it is best to reach high temperatures in a relatively short time. Copper is expensive, though, so it is not used for everyday cook-ware and bakeware. Copper also reacts with food, and it can be toxic at high levels. To prevent its reacting with food, copper cookware is typically coated with a thin protective layer, usually stainless steel or tin, on surfaces that come into contact with food.