Powdered magnesium carbonate, usually the type of chalk used by gymnasts, helps dry a climber’s sweaty hands. Chalk in climbing was pioneered by the legendary boulderer John Gill, a former gymnast. The use of chalk is controversial because it mars the rock surface with white stains, and is banned at some climbing areas. Some areas require the use of colored chalk which matches the rock’s hue. Chalk is carried in a Chalk Bag attached to either the climber’s harness with a carabiner or on a separate nylon belt or cord.