Chalk It is formed in the sea by sub-microscopic plankton, which fall to the sea floor and are then consolidated and compressed during diagenesis into chalk rock. Most people first encounter the word "chalk" in school where it refers to blackboard chalk, which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased. Blackboard chalk manufacture now may utilize mineral chalk, other mineral sources of calcium carbonate, or the mineral gypsum (calcium sulfate). While gypsum-based blackboard chalk is the lowest cost to
Liquid chalk Liquid chalk The term liquid chalk refers to several different kinds of chalk: Despite the term, some forms of "liquid chalk" contain no actual chalk. Liquid chalk can be a variation of normal chalk (see: magnesium carbonate) used to improve grip for sports, such as rock climbing, weight lifting, or gymnastics. Rock climbers use liquid chalk to prevent their hands from sweating. It may be used by climbers in situations where powdered chalk is restricted. It is preferred by athletes because it remains effective longer and leaves less residue on rocks and equipment. Liquid chalk for rock climbers is made