Chromium

Refined chromium is a hard, lustrous, steel-grey metal best known as the defining alloying element of stainless steel. Chromium additions of as little as 10.5% by mass render steel effectively immune to rust and most chemical corrosion. Beyond stainless applications, chromium is used in hardened steel alloys for armour and tooling, in hard chrome electroplating for wear-resistant surfaces, and in refractory applications owing to its high melting point. Chromite ore is first converted to ferrochromium (a crude chromium-iron alloy) in an electric arc furnace before further refining to pure chromium, making it a two-stage process.