Modified date: 11/10/2023. Chalk is a soft, white, porous, sedimentary rock composed primarily of the mineral calcite (calcium carbonate). It is often associated with marine environments and is characterized by its distinctive white color and powdery texture.

calcium carbonate (CaCO3), chemical compound consisting of one atom of calcium, one of carbon, and three of oxygen that is the major constituent of limestone, marble, chalk, eggshells, bivalve shells, and corals. Calcium carbonate is either a white powder or a colorless crystal.

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 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.

It is a chemical compound with the chemical formula CaCO3. It is a white insoluble powder-like substance which occurs naturally in minerals, chalk, marble, limestone, calcite, shells, pearl, etc. Medicinally, it is used as an antacid or as a calcium supplement. It is also used as filler in cosmetics.

The main component of chalk is calcium carbonate (CaCO 3 ), a form of limestone. Limestone deposits develop as coccoliths (minute calcareous plates created by the decomposition of plankton skeletons) accumulate, forming sedimentary layers.

Chalk (calcium carbonate) Home. Chemistry. Chemicals. Chalk, Non-Toxic. 0 out of 5 star rating. 0 Reviews. Chalk, Non-Toxic. $1.95. Box of a dozen sticks. For use in classroom and home settings. quantity. Ages 8+. In Stock & Ready to Ship. Need it fast? See delivery options in cart. Free Shipping on Most Orders $100+. Add to Wish List.

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.

Calcite is a naturally occurring calcium carbonate (CaO 3) mineral in rocks such as chalk, limestone, and marble. These rocks are the primary sources of the extender pigment. Its whiteness, softness, and fine-grained nature make it an ideal white pigment, both abundant and easily processed.

Calcium carbonate in the form of chalk has traditionally been a major component of blackboard chalk. However, modern manufactured chalk is mostly gypsum, hydrated calcium sulfate CaSO 4 ·2H 2 O. Calcium carbonate is a main source for growing biorock.