Iron Makes Up About 5% of Earth's Crust
Iron is a metallic chemical element which makes up about 5% of the Earth's crust. It's a lustrous and very workable metal that's widely used in industry. Although naturally magnetic it can be demagnetized. Its magnetic properties have helped with the study of the history of Earth. The ancient particles in rocks that aligned in different directions over thousands of years reflect changes in Earth's magnetic field.
Pure iron is a soft metal that conducts heat and electricity. Most iron that's used is alloyed with other elements particularly carbon to improve strength. Iron reacts to moisture in the air by forming an oxide known as rust.
Essential for both animal and human health iron is also necessary for the health of plants. The vast majority of iron in our bodies is in our blood. Iron rich blood cells carry oxygen around our body from our lungs. The iron is what gives blood its red colour.
The red orange and yellow colours that can be seen in some soil and rocks is mostly caused by iron oxides. The red coloured dust on Mars is also caused by iron oxides.
The inner core of the Earth is believed to be a solid iron-nickel alloy. Meteorites of iron and nickel are believed to be some of the earliest materials that formed after the formation of the universe.
In industry almost all iron ore is used to make steel and one of the principal ores of iron is the mineral hematite.