Cobalt: The Element

The element cobalt is a metal which is denoted by the chemical symbol Co. It has got its name from the German word kobalt, which means "goblin", and was used by the miners of cobalt ore. It is one such chemical element whose compounds have been in use for many centuries. Use of cobalt is found in the Egyptian sculptures and Persian jewelries that belong to the ancient period. The credit for the discovery of cobalt goes to the Swedish chemist Georg Brandt. In 1735, he demonstrated that the source of blue color in glass is due to the presence of cobalt and not because of bismuth as was believed at that time.

Usually, cobalt is not available in the metallic state and is found in the form of minerals. The mines situated in the Democratic Republic of the Congo and Zambia are the two main sources from which the largest quantity of cobalt is mined. The principal ores of cobalt from which the metal is obtained are - cobaltite, glaucdot, skutterudite and erythrite, etc. These ores have a metallic luster. Generally, cobalt is mined along with nickel and chromium, and is obtained as a by-product of their mining.

Properties of Cobalt

Cobalt in its pure form is a hard substance but brittle in nature. The appearance of pure metallic cobalt is the same as iron and nickel. It has a high melting and boiling point. Cobalt occurs in two allotropic forms. The element cobalt has an atomic number of 27 and atomic mass of 58.93. It has a variable valence of 2 and 3. So far, 26 isotopes of this element have been found. Among them, Cobalt-59 is its only stable isotope and is found naturally. There are 22 isotopes of cobalt which possess radioactive properties.

Industrial Uses of Cobalt

Cobalt is an essential component of a number of useful alloys. Stellite is an alloy of tungsten, cobalt and chromium, and is used in high-speed cutting tools. It is used with iron, nickel and some other metals in the manufacturing of Alnico, an alloy with high magnetic strength. It is also used as an ingredient in magnet steels and stainless steels. In the electroplating process, cobalt has been used as it is hard in nature and resistant towards oxidation. Salts of cobalt are used as pigment for the purpose of adding blue color to glass, enamels, tiles, porcelain, pottery, etc. Electrodes of Lithium-ion batteries contain a substantial amount of cobalt. Some of the compounds act as good oxidation catalysts in various chemical reactions. Cobalt-60 is a radioactive isotope of cobalt and is used as a source of gamma rays in radiotherapy.

Small amounts of cobalt is an essential requirement for most living organisms. In human beings, it is necessary in the form of trace nutrient. It is one of the key component of vitamin B12. Cobalt is a nutritional substance for micro-organisms like bacteria, algae and also fungi.

If the level of cobalt content in our body increases, then the effect is harmful and may even lead to cancer. On direct contact with the skin, it can cause dermatitis. Cobalt in a powdered form tends to catch fire easily.