One of the most important physical properties of chalk is its ability to store water. For industrial purposes, chalk makes a good fertilizer and cement-maker. Its permeability allows easy molding and tunneling, and its softness is useful in writing utensils.
Chalk decomposes with the application of heat, and can be used in the preparation of steel with lead ores and smelted copper. It has medicinal uses to help people with diarrhea, and is used by gymnasts and weightlifters to increase friction between surfaces. Before the Industrial Revolution, chalk was used extensively in water wells because of its permeability, which makes it a great aquifer.