1. Calcium carbonate makes up 4% of the earth's crust. Over 20% of the World's sedimentary rocks are composed of chalk or limestone.

  2. Limestone is an inorganic, sedimentary rock formed from the remains of microscopic animals or foraminifera. Chalk was also thought to be derived from foraminifera but in 1953 was shown to be largely composed of coccoliths, a lime-secreting algae. 

  3. Khufu's Pyramid, usually referred to as the "Great Pyramid", is the world's oldest structure and consists of 2.5 million limestone blocks, totalling over 6 million tonnes.

  4. Ground Chalk has been commonly known for centuries as Whiting. It is believed 'whiting' is derived from the Saxon word, 'Hwíting-melu', which literally means 'whitening powder'.

  5. Calcium is an important structural component of bones and teeth and is necessary for the normal function of all muscles and nerves.

  6. Pasta, the Italian term for dough originally referred to how painters produced their pastel chalk. They kneaded chalk, pigment powder and an aqueous binder into uniform dough from which pencils were formed and finally dried.

  7. In Shergotty, India a meteorite fell from the sky which is believed to have originated from Mars. The meteorite contained calcium carbonate, as well as traces of gypsum.

  8. The base of pastel chalks is not calcium carbonate but calcium sulphate (CaSO4), which is derived from gypsum (CaSO4-2H2O). Pastels also contain clays and oils for binding and strong pigments.

  9. Though white cliffs are common in England the only other chalk cliffs in the world, are in Northern Ireland, France, Denmark and Germany. Chalk geology is rare in the World, confined to northwest Europe; thus, it is of global importance.

  10. 14th century Welsh market traders used to try to pass chalk off as a hard cheese on unsuspecting customers, hence the popular term 'like chalk & cheese'.