Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed under the sea by the accumulation and lithification of hard parts …

: a prepared form of chalk or a material resembling chalk especially when used (as for writing on blackboards) as a crayon

chalk, 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 …

May 9, 2019 · Chalk is a soft, white sedimentary rock formed from marine microfossils. Learn its formation, mineral composition, properties, famous deposits, and uses.

CHALK meaning: 1. a type of soft white rock 2. a stick of this rock or a similar substance used for writing or…. Learn more.

Definition of chalk noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

Chalk is used in making lime, cement, and fertilizers, and as a whitening pigment in ceramics, paints, and cosmetics. The chalk used in classrooms, however, is usually artificial and not natural.

A chalk is a soft, friable variety of limestone consisting of poorly lithified calcareous ooze, produced by the accumulation of planktonic organisms in a pelagic (open sea) environment.

a piece of chalk or a substance like chalk, often coloured, used for writing and drawing on a blackboard

Blackboard chalk is not real chalk. It is really gypsum (calcium sulfate), but people call it "chalk". People use it for drawing on hard things, because it is soft. If this chalk is rubbed on something hard or …