\Chalk\, n. [AS. cealc lime, from L. calx limestone. See
{Calz}, and {Cawk}.]
1. (Min.) A soft, earthy substance, of a white, grayish, or
   yellowish white color, consisting of calcium carbonate,
   and having the same composition as common limestone.
2. (Fine Arts) 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}.
{Black chalk}, a mineral of a bluish color, of a slaty
   texture, and soiling the fingers when handled; a variety
   of argillaceous slate.
{By a long chalk}, by a long way; by many degrees. [Slang]
   --Lowell.
{Chalk drawing} (Fine Arts), a drawing made with crayons. See
   {Crayon}.
{Chalk formation}. See {Cretaceous formation}, under
   {Cretaceous}.
{Chalk line}, a cord rubbed with chalk, used for making
   straight lines on boards or other material, as a guide in
   cutting or in arranging work.
{Chalk mixture}, a preparation of chalk, cinnamon, and sugar
   in gum water, much used in diarrheal affection, esp. of
   infants.
{Chalk period}. (Geol.) See {Cretaceous period}, under
   {Cretaceous}.
{Chalk pit}, a pit in which chalk is dug.
{Drawing chalk}. See {Crayon}, n., 1.
{French chalk}, steatite or soapstone, a soft magnesian
   mineral.
{Red chalk}, an indurated clayey ocher containing iron, and
   used by painters and artificers; reddle.

\Chalk\, v. t. [imp. & p. p. {Chalked}; p. pr. & vb. n.
{Chalking}.]
1. To rub or mark with chalk.
2. To manure with chalk, as land. --Morimer.
3. To make white, as with chalk; to make pale; to bleach.
   --Tennyson.
         Let a bleak paleness chalk the door.  --Herbert.
{To chalk out}, to sketch with, or as with, chalk; to
   outline; to indicate; to plan. [Colloq.] ``I shall pursue
   the plan I have chalked out.'' --Burke.