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Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor.
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The meaning of CHALK is a soft white, gray, or buff limestone composed chiefly of the shells of foraminifers. How to use chalk in a sentence.
Oct 10, 2023 · Chalk is white or pale gray, fine-grained, and soft, with a powdery texture. It has a high calcium carbonate content, is chemically reactive, and can effervesce in contact with acids. Chalk is historically used in education and art, and its softness makes it ideal for rock climbing and gymnastics.
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.
Made How. Volume 1. 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.
chalk noun (FOR DRAWING) [ C or U ] a stick of this rock or a similar substance used for writing or drawing: He picked up a piece of chalk and wrote the answer on the blackboard. coloured chalks.
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.
Artists often place chalk into holders to keep their hands clean and protect drawings from smudging. Inherently cohesive, yet powdery, chalk of all colors readily adheres to paper and produces marks with little pressure and minimal crumbling. When the chalk is dense and hard, it can make narrow lines and precise images.
