What is the white powder that James rubbed on his hands before the game?

Magnesium dust

Gymnasts often put a layer of white powder on their palms before doing gymnastics on the equipment and before lifting barbells by weightlifters, and sometimes put some on the equipment. What is this white powder? Why do you want to put on this white powder?

This white powder is called "magnesium carbonate", and people usually call it "magnesium powder". Magnesium carbonate has light weight and strong hygroscopicity. When athletes compete, their palms often sweat, which is very unfavorable for gymnasts and weightlifters. Because the wet palm will reduce the friction, so that athletes can't hold the equipment, which not only affects the quality of movement, but also makes athletes fall off the equipment, causing mistakes and even injuries. Magnesium carbonate can absorb sweat from the palm and increase the friction between the palm and the instrument. In this way, athletes can hold the equipment tightly, which is conducive to improving the quality of action.