Iron is a chemical element with the symbol Fe (from Latin: ferrum) and atomic number 26. It is a gray, rough transition metal. Iron is extracted from iron ore, mined in iron mines located in large parts of the world.
Colloquially, the term iron is often used for a material that is actually called steel, an alloy of iron and carbon.
Excavations show that around 4000 BC. iron was already used in Sumer and Ancient Egypt for spearheads and ornaments. The iron for this often came from impacted meteorites (the so-called meteor iron). Tutankhamun's iron dagger was probably made of meteor iron.
In the following centuries, the use of iron spread to Mesopotamia, Anatolia and the Middle East. Iron was an extremely expensive metal in those days. From the merchants of the kārum Kaneš from ca. the 19th century BC. For example, we know that one shekel of iron yielded between 40 and 95 shekels of silver. Only after it was discovered how to extract iron from its ores on a large scale and then forge it did it become an affordable substance and its use boomed. Ironworking was introduced to Greece in the late 11th century BC. From Greece it quickly spread across Europe.
Between the 12th century BC. and the 10th century BC. iron took the place of bronze in the production of tools and weapons. This transition from bronze to iron, which ushered in the Iron Age, was caused not so much by better properties of iron, but more by the greatly diminished availability of tin, a main component of bronze. In the Middle East, it was discovered that quality could be improved by heating the raw iron ore in a bed of charcoal. Later this process became known as carbonization. In China, the principle of the blast furnace was devised and the quality of the iron could be further improved. More carbon then came into the iron, which already resulted in a kind of steel.
The word iron, from Middle Dutch isering, comes from the Proto-Germanic *īsarnan, from which Nederduits Iesen, German Eisen, English iron, Danish jern originated. In the period of the La-Tène culture (last 500 years BC) it is borrowed from Gallic īsarnon (compare Irish iarann and Welsh haearn). One assumes derivation from the Proto-Indo-European *ésh₂r̥ 'blood'.
Applications and usage possibilities
Iron is the most commonly used of all known metals, nowadays especially in the form of steel. Because it is cheap and strong, it is used for example for cars, ships and for building large structures.
Other uses of iron include:
In transformers (as soft iron or as ferrite).
Cast iron, where the molten iron is poured into a refractory mould. See also: Iron rudder.
Wel iron, also called drawn iron.
Wrought iron, formerly handcrafted by a blacksmith in a forge.
As a catalyst in the Haber-Weiss reaction
Iron, like nickel and cobalt, is a ferromagnetic metal. The core of the most abundant iron isotope iron-56 has the second highest binding energy (per nucleus) of all elements, making iron the heaviest element that can be made exothermic by fusion and the lightest element that can be made by nuclear fission without loss of energy. This explains why the element is very common in the universe. The total mass of iron in the universe is more than 100 times that of all the heavier elements combined. At 32.1%, iron is the element most abundant in the earth's composition.
The Earth's crust is made up of about 5% iron, most commonly found as the mineral hematite; iron(III) oxide (Fe2O3). Pure iron is isolated from this by reducing the ore with carbon at a high temperature. In almost all parts of the w