Iron is the fourth most abundant element by mass in the Earth's crust. It is believed that the Earth's core consists mainly of iron with nickel and sulfur.
The earliest iron objects found in Egypt date back to about 3500 BC. They contain about 7.5% nickel, which indicates a meteoritic origin.
The ancient Hittites of Asia Minor, today's Turkey, were the first to smelt iron from their ores around 1500 BC, and this new, stronger metal gave them economic and political power. The Iron Age has begun.
Some types of iron were clearly superior to others in terms of carbon content, although this was not appreciated. Some iron ore contained vanadium, from which so-called Damascus steel was made, ideal for making swords.
The first person to systematize different types of iron was René Antoine Ferchot de Réaumur. In 1722, he published a book explaining how steel, wrought iron, and cast iron differ in their charcoal (carbon) content.
Hematite is the most common iron-containing ore, but iron is also found in other minerals, such as magnetite and taconite.
On an industrial scale, iron is produced in a blast furnace by heating hematite or magnetite with coke (carbon) and limestone (calcium carbonate). This produces cast iron, which contains about 3% carbon and other impurities.
Pure iron is used for the manufacture of transformer cores and electric motors, electromagnets and microphone membranes. But the main structural materials in almost all branches of modern production are iron alloys — cast iron (used for steel production) and steel.
There are many different types of steel with different properties and uses. Ordinary carbon steel is an iron-carbon alloy (from 0.1% for low-carbon steel to 2% for high-carbon steel) with small amounts of other elements.
Alloy steels are carbon steels with other additives such as nickel, chromium, vanadium, tungsten, and manganese. They are stronger and stiffer than carbon steels and have a huge variety of uses, including building bridges, electric supports, making bicycle chains, cutting tools, and rifle barrels.
Stainless steel is highly resistant to corrosion. It contains at least 10.5% chromium. Other metals, such as nickel, molybdenum, titanium, and copper, are added to improve strength and workability. Stainless steel is used in architecture, bearings, cutlery, surgical instruments and jewelry.
Cast iron contains 3— 5% carbon. It is used for pipes, valves and pumps. It's not as strong as steel, but it's cheaper.
In a free state, iron — silver-white metal, very ductile, heavy, refractory (melting point — 1539°C). Its characteristic feature is its magnetic properties.
The atomic number is 26. Symbol — Fe (lat. “ferrum”). Boiling point — 2862°C, density — 7.874 g/cm³
1. The average amount of iron in the human body is about 4.5 g.
2. When people first learned how to extract iron and process it, it cost more than gold.
3. The largest piece of pure iron ever discovered weighs 66 tons. This is all that remains of a meteorite that once fell on the African country of Namibia.
4. Every 45-47 minutes, as much iron is extracted from the Earth's interior as gold has been mined in history.
5. Greenland is one of the few places where there are deposits of pure native iron without impurities.
