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What Is Chalk? Chalk is a variety of limestone composed mainly of calcium carbonate derived from the shells of tiny marine animals known as foraminifera and from the calcareous remains of marine algae known as coccoliths. Chalk is usually white or light gray in color. It is extremely porous, permeable, soft and friable.
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 varieties contain up to 99 percent calcium carbonate in the form of the mineral calcite.
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.
[noncount] : a type of soft, light-colored rock. Chalk is a kind of limestone. 2. a [noncount] : a substance that is made into white or colored sticks and used for writing or drawing. The teacher handed her a piece of chalk and asked her to write the answer on the chalkboard.
Chalk is a type of limestone. It was made by calcareous (CaCO 3) skeletons of tiny planktonic algae called coccoliths. They live in the sea in huge numbers. They make chalk (CO 2) as a by-product of their photosynthesis. The chalk cliffs of Dover and elsewhere were made when England was below the equator in a tropical sea.
Jun 8, 2018 · Earth and the Environment. Geology and Oceanography. chalk. Chalk. views 3,128,851 updated Jun 08 2018. Chalk. Background. Chalk used in school classrooms comes in slender sticks approximately .35 of an inch (nine millimeters) in diameter and 3.15 inches (80 millimeters) long.
noun. us / tʃɑːk / uk / tʃɔːk / chalk noun (ROCK) Add to word list. [ U ] a type of soft white rock. chezzzers/ iStock / Getty Images Plus/GettyImages. Geology: types of rock. agglomerate. arenaceous. arenite. asthenosphere. asthenospheric. emery. flinty. gneiss. hematite. indurated. intrusive. lahar. limestone. lodestone. magma. marcasite. marl.
