Cobalt is a chemical element with the symbol Co and atomic number 27. It is a hard, lustrous, silver-gray metal that is commonly found in minerals such as cobaltite, erythrite, and skutterudite.
Cobalt is an essential element for humans in small amounts, but prolonged exposure to high levels of cobalt can lead to lung and heart problems. Proper handling and disposal of cobalt-containing materials are necessary to prevent environmental contamination.