Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth's crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.
Cobalt-based blue pigments (cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was later thought by alchemists to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold.
see Cobalt therapy.
Cobalt-chromium (CoCr) is a metallic alloy composed of cobalt and chromium, often used in medical and dental implants due to its strength, durability, and biocompatibility. It is commonly used in orthopedic implants such as hip replacements, as well as in cardiovascular devices such as stents and heart valve replacements. The use of cobalt-chromium in medical devices has been associated with some concerns, such as corrosion and wear leading to metal ion release and potential toxicity, as well as hypersensitivity reactions in some patients. However, advances in material science and design have helped to minimize these risks and improve the safety and efficacy of cobalt-chromium medical implants.