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 Most people first encounter the word "chalk" in school where it refers to blackboard chalk, which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased.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 However, some gyms require liquid chalk because it leaves less residue on gym equipment. Liquid chalk adheres to the hand better, reducing the need to re-chalk. Some liquid-chalk mixtures for climbing are made with magnesium carbonate, colophony, and ethanol or an alcohol that dissolves the colophony and quickly evaporates from the solution (as isopropyl alcohol or ethanol). Sometimes, resin or rosin is added to increase gripping properties or an additive for aroma is included because of the bad smell of spirit. Sports liquid chalk is sold in bottles. The user takes a small amount into their palms, spreading the chalk