Iron is the most abundant metal on earth, and is one of the three magnetic elements. In the year 2007, 2 billion metric tonnes of iron ore were mined. Iron, and its most common alloy steel, are also produced in substantial quantities from the recycling of scrap metal.
Physical properties: Pure iron has a metallic color, with a slight tinge of gray. However, it oxidizes easily, and then it takes on a dark gray color. Iron is a magnetic material, and is the most used metal on earth, with hundreds of everyday uses, including the production of steel. It melts at 1538C, and boils at 2862C. Iron is moderately dense (7.87 gram/cm3) and quite hard (4.0 on a 10 point scale).
Chemical properties: When iron reacts with oxygen, it forms a reddish-brown oxide we call rust. Iron reacts readily with air and water, so items that need to last wear and tear while being left out in the open e.g. cars, are not made from pure iron. Instead, most iron items in modern times are coated with another metal, like chromium, to prevent rusting.
In the medieval science of alchemy, the alchemists decided that every metal had some heavenly body it related to. Iron was related to the planet Mars.
History: The iron that was used by pre-historic people came from meteors. Iron was first smelted in 2000 BC, and cast iron was first produced by the Chinese in 550 BC. Europe did not learn of cast iron until the medieval times. Steel has been known since ancient times. During the 17th century and the Industrial Revolution, many people discovered steel could be made by mixing iron and carbon. Later, various methods of strengthening steel were discovered. Slowly, the making of steel became one of the primary uses of iron. The development of steel meant that pure iron was no longer used by the world. Because iron is magnetic, many civilizations have used iron to make compasses for navigation across land and sea.
Production: 90% of all metallic ores mined is iron ore. Iron ore is processed in a blast furnace. First oxygen is fired at the ore, and it reacts with and separates some impurities. A type of coal called coke (mostly carbon) is burned at the bottom of the furnace, and the heat melts the ore. The impurities rise to the top of the liquid and are removed, allowing the molten metal to be separated out and cooled into "pig iron". Pig iron is brittle and hard, and can be cast into different shapes using moulds. For other uses, pig iron is further treated to remove carbon and other impurities to produce steel and other alloys. The top five producers of iron ore are China, Brazil, Australia, India and Russia. Pie Chart of Top 5 Iron Producing Countries...
Uses: When iron is alloyed with carbon, it produces steel. Steel is iron, with a small amount of carbon in it. If too much carbon is added to steel, it cracks easily. By blowing air through molten steel, the oxygen burns off the excess carbon. Many steels have other metals like manganese and tungsten combined as well to give them special properties. Because of its low cost and high strength, steel is used to make machinery, cars, the hulls of ships like oil tankers, and structural frames for buildings of all sizes, from skyscrapers to farmhouses. Since iron and steel react easily with air and water, they are often plated with another material such as chromium to prevent rusting.
Health: All living organisms need iron to survive. Iron is stored in cells, and iron deficiency can lead to anaemia. Iron is an important part of the oxygen-carrying protein, haemoglobin, without which respiration and life itself would be impossible. The body does not let its iron stores fall into the hands of bacteria, because iron makes bacteria stronger and more dangerous to the body's immune system. Good sources of iron for the body are meat, fish, lentils, beans, leafy vegetables, tofu, peas, fortified bread, and fortified breakfast cereals. Blood donors and pregnant women need more iron in their diet.
Sparrow, Giles. Zinc: The Elements, 1999, Marshall Cavendish, USA.
Iron, Wikipedia. <http://en.wikipedia.org/wiki/Iron> accessed on 22-Feb-2009.
Iron Ore, Mineral Information Institute. <http://www.mii.org/Minerals/photoiron.html> accessed on 20-March-2009.