Iron is a chemical element with the symbol Fe (from Latin ferrum 'iron') and atomic number 26.

It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust, after oxygen, silicon, and aluminium.

Iron's abundance in rocky planets like Earth is due to its abundant production during the runaway fusion and explosion of type Ia supernovae, which scattered iron into space.
Electric currents in the liquid outer core are believed to be the origin of the Earth's magnetic field. The other terrestrial planets, Mercury, Venus, and Mars, as well as the Moon, are believed to also have a metallic core consisting mostly of iron. Mars in particular has long been known for its rust. Iron on its surface, combined with water and oxygen from its past, give Mars its red hue.



Metallic iron is rarely found on the surface of the Earth because it oxidizes as it combines with oxygen to produce iron oxide, commonly known as rust. This is an exothermic reaction, but the heat produced is small and quickly dissipates into the surroundings. Unlike the oxides of some other metals that form protective layers, such as aluminum, iron rust occupies more volume than the metal itself, and flakes off, exposing fresh surfaces for corrosion.

Extracting usable metal from iron ores requires kilns or furnaces capable of reaching 1,500 °C, about 500 °C higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys such as bronze. That event is considered the transition from the Bronze Age to the Iron Age. However, iron artefacts of great age are much rarer than objects made of gold or silver due to how easily iron corrodes.

In the modern world, iron alloys such as steel, stainless steel, cast iron and special steels, are by far the most common industrial metals, due to their mechanical properties and low cost.

The iron and steel industry is very important economically, and iron is the cheapest metal, with a price of a few dollars per kilogram.

Types of Iron
  • Cast Iron
    Cast iron is made by smelting iron with carbon, silicon, and other metal alloys. Once the iron is heated and molten, it is poured into different casts and molds to create a wide array of different products, such as cast iron frying pans.

  • Wrought Iron
    Wrought iron was one of the first iron metals created by blacksmiths. It is made by heating iron in a furnace until it reaches the desired temperature. Next, the blacksmith hammers and shapes the iron into various shapes, depending on the product being produced. Wrought iron can be reheated, so it can be bent, shaped, and hammered more. Unlike other types of iron, wrought iron is mostly pure iron, with very little carbon or other materials. As a result, it is very durable, making it useful for doors, gates, and railings. Before steel was invented and began to be used widely in construction (about 1914), wrought iron was a popular building material used for support beams.

  • White Iron
    White iron is a type of cast iron. It is made by removing the graphite from the cast iron. The removal of the graphite is what gives white iron its colour. However, while white iron provides decent wear resistance, it is very brittle. As such, it is not uncommon to use cast iron under the white iron, so the white iron is merely on the outside of the finished product.

  • Gray Iron
    Gray iron is another form of cast iron. It gets its colour from the graphite in the iron that has been fractured. This iron metal is wear-resistant and has anti-corrosive properties. Gray iron is sometimes used for exterior applications in place of wrought iron.

  • Ductile Iron
    Ductile iron is also a different type of cast iron. It is made by adding magnesium to the cast iron alloy. The addition of magnesium causes a chemical reaction where the graphite will transform into a spherical shape instead of fracturing, as with gray iron. It is possible to make different grades of ductile iron by controlling the amount of magnesium added and the amount of heat applied during the manufacturing processes.

  • Malleable Iron
    Malleable iron is made by continuing to heat and cool white iron. By continuing to heat and cool the iron, it releases graphite molecules. Malleable iron products have the ability to bend without breaking and offer better tensile strength. Uses of this iron include fence fittings, washers, pipe fittings, tools, farm equipment, machine parts, and electrical fittings.
Iron is one of the elements known to the ancient world, and has been used for millennia. The technology developed slowly, and even after the discovery of smelting, it took many centuries for iron to replace bronze as the metal of choice for tools and weapons.

Smelting is the process by which a metal is obtained, either as the element or as a simple compound, from its ore, by heating it beyond the melting point in the presence of oxidizing agents such as air, or reducing agents, such as coke. Coke is a solid fuel made by heating coal in the absence of air so that the volatile components are driven off.

The first metal to be smelted in the ancient Middle East was probably copper, followed by tin, lead, and silver. To achieve the high temperatures required for smelting, furnaces with forced-air drafts were developed; for iron, temperatures even higher were required. Smelting thus represented a major technological achievement. Charcoal was the universal fuel until coke was introduced in 18th-century England. Meanwhile, the blast furnace had achieved a high state of development.

   Making steel

Steel is made from iron ore, which is a compound of iron, oxygen, carbon, and traces of other minerals that occur in nature. The raw materials for steelmaking are mined and then transformed into steel using two different processes: the blast furnace and the electric arc furnace.

Oxygen Blast Furnaces

Basic oxygen steelmaking uses carbon-rich pig iron, made by smelting iron ore in a blast furnace, resulting in a high carbon content, along with silica and other impurities, making it brittle and not otherwise useful. Blowing oxygen through molten pig iron converts some of the carbon in the iron into CO and CO2, removes silicon and phosphorus, and turns the iron into steel.

By 2013, 70% of global steel output was produced using this basic oxygen furnace method. Furnaces can convert up to 350 tonnes of iron into steel in less than 40 minutes.

Electric Arc Furnaces

Electric arc furnaces manufacture steel from scrap iron. They use high-power electric arcs to melt the scrap. In an electric arc furnace, a batch of iron is loaded into the furnace, 400 tonnes at a time. Gas burners may be used to assist with melting.

To produce a ton of steel in an electric arc furnace requires approximately 440 kWh per tonne. This process allows larger alloy additions than the basic oxygen method. The electric arc furnace creates valuable slag as a by-product, just as the blast furnace does.

Stainless steel is an alloy of iron and several other elements, such as nickel, chromium, molybdenum, and carbon, that is more resistant to corrosion than plain iron or steel.

Steelmaking is one of the most carbon emission intensive industries in the world. As of 2020, steelmaking is responsible for about 10% of greenhouse gas emissions. To mitigate global warming, the industry will need to find significant reductions in emissions.

Iron in the Body

The body of an adult human contains about 4 grams of iron, mostly in the hemoglobin and myoglobin. These two proteins play essential roles in oxygen transport by blood and oxygen storage in muscles.

Iron is a mineral that is naturally present in many foods, and sometimes added to some food products, and available as a dietary supplement. Iron is an essential component of hemoglobin, a red blood cell protein that transfers oxygen from the lungs to the tissues.


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