Iodine

Iodine is a nonmetal in the halogen family. Its dark, shiny crystals give off a distinctive violet vapor. Your body needs small amounts of iodine to make thyroid hormones; iodized salt supplies it in the form of iodide or iodate compounds. Iodine-containing compounds also help doctors see organs and blood vessels clearly in X-ray images by absorbing X-rays. In nature, iodine occurs in compounds in mineral deposits and salty underground waters called brines. Major commercial sources are Chile's nitrate-rich caliche deposits and brines in Japan. Producers dissolve iodine compounds from the deposits or recover them from brines, then use chemical reactions to release iodine before separating and purifying it.