Making up over a fifth of the earth’s crust, Iron is the 4th most common element that can be found in our planet's crust (the most common being oxygen, followed by silicon and then aluminium). Iron is found and mined from a number of rocks which can vary greatly in their iron content. These rocks are referred to as iron ore, and the iron inside is generally found in the form of Hematite, Magnetite, Goethite, Limonite or Siderite. Each one is comprised of different levels of iron as well as other elements and minerals, for example Hematite has a chemical symbol of Fe2O3, ‘Fe’ symbolising iron, and ‘O’ oxygen. From this we know that the ore is comprised of 2 elements and for every 2 iron atoms there is 3 Oxygen atoms, essentially it is 40% iron.

Iron has been used by humans for over 3500 years and was instrumental in the development of our early civilisations. The period of iron's most prolific use and development is known as the Iron Age, which lasted for 1900 years, between 1200BC and 700AD. This does not however signify the time in which iron was discovered and first used, as there is evidence of iron being used as early as 3200BC. At this stage it was a rare commodity and its uses were not realised or put to use, rather iron was used decoratively in what would have, at the time, been very precious jewellery. Due to the difficulty of mining and refining iron ore at this time, it is commonly believed that this iron was not mined from ore as it traditionally has been for millennia, but rather that it was gathered from small deposits of pure iron that fell to earth on a meteorite.

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As previously mentioned, iron is found in abundance in the earth’s crust so very little digging has to be done to reach its deposits, relatively speaking. The issue that the people of the Bronze Age (the age immediately preceding the Iron Age) found that prevented its use was the difficulty with which it was extracted from its ore. At the time the most common metals in use were copper and tin, both of which can be easily shaped without the need to apply heat, and tin, if needs be, could be reduced to its liquid form at around 232oC, which was perfectly achievable at the time by use of a kiln (an oven like device in use since 6000BC). Some types of kilns could even reach the 1000/1200oC temperature that was required to reduce copper to a liquid but no kiln, even those made today, can reach the 1520oC that is required to melt iron.

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Having said that, melting iron was never the goal; all that was needed was a way to make it malleable, which can be done once it reaches 800oC. But a kiln offers an inhospitable environment to humans and to heat the iron in the kiln and then remove it to hammer would be an inefficient way to shape it as it would quickly cool down and harden once removed. The need for iron alternatives to bronze was becoming desperate, spurred on by a multitude of factors, such as a tin shortage epidemic that struck between 1500BC and 1300BC.

Fortunately methods of effective iron-working had been developed as early as 1800BC in the Indian Sub-Continent and these methods were being shared and quickly adapted elsewhere. By 1200BC, despite the shortage of bronze materials being resolved, iron implements were known to be stronger, harder, cheaper and lighter; as a result bronze materials never recovered their popularity and former wide-spread use.

The Iron Age symbolises the wide spread use of iron in agricultural, military and domestic settings. The iron used at the time was called Wrought Iron which, in itself, is not a pure iron as, in its purest form, iron is barely harder than its bronze counterparts. Wrought iron was created in a Smith’s forge and it was not made so much as it was shaped by the application of heat and hammer. During the heating process the iron would become soft and absorb some of the carbon which emanated from the forge’s charcoal fire, and though it would only make up 0.05% of the end result, the small amount of carbon would afford wrought iron a great deal more strength than it would otherwise have had.

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The Iron Age would last well into the 8th Century, but its end did not mean the end of iron. After the Iron Age came the Medieval Period, also known as the Middle Ages, which was a time remembered for its social reforms, vast urban migrations and its Kings, Queens, Bishops and Popes. Basically it was not symbolised by the prevailing material in use at the time, so despite the end of its age, iron still made up the majority of the tools and weapons used, and continued to do for an additional 1000 years.

Those 1000 years saw great developments and improvements in iron manufacturing, such as the development of the blast furnace in the 12th century and the production of Cast Iron in the 15th century. Cast iron differed from wrought iron as the blast furnace would subject iron ore to the level of heat that would easily melt iron and allow carbon to be absorbed in abundance, to the point that carbon would make up anywhere between 2% and 4.5% of the final product. Cast Iron was an inappropriate material for weapons, as it was brittle and would shatter even under the force of a blacksmith’s hammer; instead it was used for domestic items, decorations and later in the manufacture of steam trains.

Iron remained the go-to metal until the 18th century and the advent of 'steel', an iron alloy with all the benefits of wrought and cast iron as well as a few unique qualities of its own. Iron remains an abundant material, with ore reserves on every continent in the world, including Antarctica. It is still mined and used today for the creation of steel, other alloys and compounds as well as just by itself. Blast furnaces remain the primary method of smelting iron, although they have had a number of upgrades over the centuries to make them capable of reaching higher temperatures and more efficient at getting rid of the impurities that iron ore naturally contains.


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