What is the chemical formula of chalk?

Hint: Chalk is calcium carbonate in chemical terms. Its formula is CaCO3. The chalk is usually white. We have used chalks in schools. These are slightly different from the original chalks. The chalk, calcium carbonate is purely a calcite mineral with only a little percentage of other minerals. Chalks have many uses apart from being used in schools for writing. Complete answer: Chalk is a common name of the compound calcium carbonate. Its chemical formula is CaCO3. Calcium carbonate is a form of limestone. Chalk is a common substance found everywhere. It is a soft, highly porous, white sedimentary carbonate rock of limestone. It is composed of calcite shells or skeletons of planktons. Chalk is pure calcite with only 2−4% of other mineral content. It forms effervescence when it comes in contact with an acid. The chalk was formed over millions of years from the protective coverings of small organisms like phytoplankton that lived in the seas and oceans. When these organisms died their protective coverings fell to the ocean bed. And they accumulated. Earth movements caused some of these deposits to experience extremely high temperatures and pressures, forming chalk. Chalk has a greater resistance to weathering and slumping than the clays. It can hold water as it is highly porous. This is a great advantage for the areas that suffer from drought and that have large amounts of limestone. Because limestone can provide a natural reservoir in these areas that release water slowly. Chalk is used for making lime and Portland cement and as a fertilizer. Chalk can be natural as well as man-made. Note: The most common form of chalk that is known to us is the blackboard chalk. In schools, we use these blackboard chalks. It is originally made of mineral chalk. They are used for drawing or writing on rough surfaces because the particles of the chalk adhere to these surfaces and are easily crumbled. The modern wood chalks are generally made up of mineral gypsum (calcium sulfate).