Chromium compounds are also used to anodize aluminum, a process which coats aluminum with a thick, protective layer of oxide. Potassium dichromate (K 2Cr 2O 7) is used in the tanning of leather while other chromium compounds are used as mordants, materials which permanently fix dyes to fabrics.

Rubies and emeralds also owe their colors to chromium compounds. Chromic oxide (Cr 2O 3), also known as chrome green, is the ninth most abundant compound in the earth's crust and is a widely used green pigment. Lead chromate (PbCrO 4), also known as chrome yellow, has been used as a yellow pigment in paints.

Other chromium-steel alloys are used to make armor plate, safes, ball bearings and cutting tools.Ĭhromium forms many colorful compounds that have industrial uses. Chromium is added to steel to harden it and to form stainless steel, a steel alloy that contains at least 10% chromium. Chromium can be polished to form a very shiny surface and is often plated to other metals to form a protective and attractive covering. Today, chromium is primarily obtained by heating the mineral chromite (FeCr 2O 4) in the presence of aluminum or silicon.Ĭhromium is a blue-white metal that is hard, brittle and very corrosion resistant. Although he believed a method for isolating chromium didn't yet exist, Vauquelin was pleasantly surprised in 1798 to discover that he was able to obtain metallic chromium by simply heating chromium oxide in a charcoal oven. He produced chromium oxide (CrO 3) by mixing crocoite with hydrochloric acid (HCl). Chromium was discovered by Louis-Nicholas Vauquelin while experimenting with a material known as Siberian red lead, also known as the mineral crocoite (PbCrO 4), in 1797.