Chalk

A soft, earthy substance, of a white, grayish, or yellowish white color, consisting of calcium carbonate, and having the same composition as common limestone.

Finely prepared chalk, used as a drawing implement; also, by extension, a compound, as of clay and black lead, or the like, used in the same manner. See Crayon.

To rub or mark with chalk.

To manure with chalk, as land.

To make white, as with chalk; to make pale; to bleach.

an amphetamine derivative (trade name Methedrine) used in the form of a crystalline hydrochloride; used as a stimulant to the nervous system and as an appetite suppressant

a soft whitish calcite