Cr • Atomic Number 24
Chromium
Chromium is a hard, steel-gray transition metal. The name derives from chroma, the Greek word for color, as chromium compounds appear in many different hues. While it is relatively abundant in the Earth’s crust, it does not occur in pure form in nature. Most ores consist of the mineral chromite.
Trivalent chromium is considered an essential trace element, with dietary needs typically met through a balanced diet. While chromium(III) is beneficial in small doses, hexavalent chromium is toxic, carcinogenic, and mutagenic.
One of the main uses of chromium is in ferrochrome, an iron alloy containing about 60 percent chromium. Chromium alloys are used in the production of oil pipelines, automotive trims, and cutlery, contributing to their shine.
Chromite is also used as a refractory material and as a raw material for producing chromium chemicals.
Major chromium-producing countries include South Africa, India, Kazakhstan, and Turkey.
The largest chromium mine in the world is the Kemi Mine in Finland, operated by Finnish steel producer Outokumpu.
The largest known chromite deposit globally is the Bushveld Complex in South Africa.
In both the EU and the USA, chromium is classified as a critical raw material.
Crocoite (red lead ore) was one of the first chromium minerals to be discovered. In Persia and during the Qin Dynasty in China, it was used to produce pigments for bright yellow-orange colors in ceramics. Chromium oxide green has been used for centuries to color glass or enamel. Vincent van Gogh, for example, used "chrome yellow" in his famous Sunflowers series, which includes a total of seven paintings.
In 1761, German mineralogist Johann Gottlob Lehmann analyzed a red-orange mineral from Siberia, later identified as crocoite. In 1797, French chemist Nicolas-Louis Vauquelin isolated chromium oxide and, by heating it with carbon, obtained chromium metal. Pure chromium was first produced in 1894 by Hans Goldschmidt using the aluminothermic process. The simpler carbon reduction previously used by Vauquelin also produced chromium carbide alongside the metal.
At the beginning of the 19th century, chromium compounds were used in dyes, paints, and tanning agents.
In the 1820s, chromium plating (electroplating) was developed to improve the durability and shine of metals. By the end of the 19th century, it was discovered that adding chromium to iron produced stainless steel. Since then, chromium has been an essential component in stainless steel products such as cutlery, machinery, and construction materials.
During World War II, chromium was considered a strategic material for armor plating, aircraft engines, and weapons. In the post-war era, chrome plating became widespread in automotive parts (bumpers, trim) and household items.
Due to the presence of toxic hexavalent chromium (Cr⁶⁺) in industrial waste, chromium poses a significant environmental risk.
About 45.000 tons of chromium are mined annually.
The majority is used in the metallurgical industry. Approximately 70 percent of chromium goes into stainless steel products alone. Other applications in the metal industry include iron alloys (ferrochromium) used in steel production to increase strength and corrosion resistance. Chromium is also a component of superalloys and tool steels for jet engines and gas turbines.
On chrome-plated faucets, bumpers, and motorcycle parts, the metal provides shine, corrosion resistance, and protection against wear.
Chromium oxide serves as a pigment for green shades in paints, ceramics, and glass, as well as a refractory material, for example in heat-resistant bricks for furnaces. Chromite is also added to bricks and stones to make them fireproof.
Although chromium compounds cover the entire color spectrum, only a few of them are used as pigments.
China is the leading producer of ferrochromium and stainless steel, as well as the largest consumer of chromium.
90 percent of the chromium mined worldwide comes from chromite deposits. Other chromium minerals include crocoite, uvarovite, eskolaite, and chromdiopside.
Global resources amount to over 12 billion tons of chromite, enough to meet demand for centuries. Geographically, 95 percent of the world’s chromium deposits are concentrated in Kazakhstan and Southern Africa.
The largest chromium producers include South Africa, India, Kazakhstan, and Turkey.
The largest active chromium mine in the world is the Kemi Mine in Finland, operated by the Finnish steel producer Outokumpu.
The world’s largest chromite deposit is the Bushveld Complex in South Africa.
Chromium is irreplaceable for its most important applications, neither in stainless steel nor in superalloys.
Chromium-containing scrap can substitute for ferrochrome in some metallurgical applications.
Critical and Strategic Metals
