chalk

chalk
—chalklike, adj.
/chawk/, n.
1. a soft, white, powdery limestone consisting chiefly of fossil shells of foraminifers.
2. a prepared piece of chalk or chalklike substance for marking, as a blackboard crayon.
3. a mark made with chalk.
4. a score or tally.
v.t.
5. to mark or write with chalk.
6. to rub over or whiten with chalk.
7. to treat or mix with chalk: to chalk a billiard cue.
8. to make pale; blanch: Terror chalked her face.
v.i.
9. (of paint) to powder from weathering.
10. chalk up,
a. to score or earn: They chalked up two runs in the first inning.
b. to charge or ascribe to: It was a poor performance, but may be chalked up to lack of practice.
adj.
11. of, made of, or drawn with chalk.
[bef. 900; ME chalke, OE cealc < L calc- (s. of calx) lime]

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Soft, fine-grained, easily pulverized, white-to-grayish variety of limestone, composed of the shells of minute marine organisms.

The purest varieties contain up to 99% calcium carbonate in the form of the mineral calcite. Extensive deposits occur in western Europe south of Sweden and in England, notably in the chalk cliffs of Dover along the English Channel. Other extensive deposits occur in the U.S. from South Dakota to Texas and eastward to Alabama. Chalk is used for making lime and portland cement and as a soil additive. Finely ground and purified chalk is known as whiting and is used as a filler, extender, or pigment in a wide variety of materials, including ceramics, putty, cosmetics, crayons, plastics, rubber, paper, paints, and linoleum. The chalk commonly used in classrooms is a manufactured substance rather than natural chalk.

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▪ rock
      soft, fine-grained, easily pulverized, white-to-grayish variety of limestone. Chalk is composed of the shells of such minute marine organisms as foraminifera, coccoliths, and rhabdoliths. The purest varieties contain up to 99 percent calcium carbonate in the form of the mineral calcite. The sponge spicules, diatom and radiolarian tests (shells), detrital grains of quartz, and chert nodules (flint) found in chalk contribute small amounts of silica to its composition. Small proportions of clay minerals, glauconite, and calcium phosphate also are present.

      Extensive chalk deposits date from the Cretaceous Period (144 to 66.4 million years ago), the name of which is derived from the Latin word (creta) for chalk. Such deposits occur in western Europe south of Sweden and in England, notably in the chalk cliffs of Dover along the English Channel. Other extensive deposits occur in the United States from South Dakota south to Texas and eastward to Alabama.

      Like any other high-purity limestone, chalk is used for making lime and portland cement and as a fertilizer. Finely ground and purified chalk is known as whiting and is used as a filler, extender, or pigment in a wide variety of materials, including ceramics, putty, cosmetics, crayons, plastics, rubber, paper, paints, and linoleum. The chief use for chalk whiting, however, is in making putty, for which its plasticity, oil absorption, and aging qualities are well suited. The chalk commonly used in classrooms is a manufactured substance rather than natural chalk.

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Universalium. 2010.

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Look at other dictionaries:

  • chalk — chalk·er; …   English syllables

  • Chalk — (ch[add]k), 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… …   The Collaborative International Dictionary of English

  • chalk — [chôk] n. [ME < OE cealc < L calx, lime, limestone: see CALCIUM] 1. a white, gray, or yellowish limestone that is soft, porous, and easily pulverized, composed almost entirely of calcite from minute sea shells 2. any substance like chalk in …   English World dictionary

  • Chalk — Chalk, v. t. [imp. & p. p. {Chalked}; p. pr. & vb. n. {Chalking}.] 1. To rub or mark with chalk. [1913 Webster] 2. To manure with chalk, as land. Morimer. [1913 Webster] 3. To make white, as with chalk; to make pale; to bleach. Tennyson. [1913… …   The Collaborative International Dictionary of English

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  • chalk... — chalk..., Chalk... [ç...] vgl. ↑chalko..., Chalko …   Das große Fremdwörterbuch

  • chalk up to — chalk (something) up to (something else) to say that something is caused by something else. She doesn t even bother to say thank you, but I just chalk it up to bad manners and try not to let it bother me …   New idioms dictionary

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