Chromium and its compounds

Chromium is an odourless, hard, steel-grey coloured metal that takes a high polish. It melts at about 1860 0C. The principal ore is chromite, which is found in Zimbabwe, Russia, South Africa, Turkey and Iran. All compounds of chromium are coloured.The principal ore from which chromium is extracted is chromite. Chromium has three main valence forms - metallic chromium(0), chromium(III) and chromium(VI). Chromium(III) or trivalent chromium occurs naturally in the environment (e.g. in chromite) and is an essential dietary nutrient. Metallic chromium(0) and chromium(VI) or hexavalent chromium are produced by industrial processes.