Iridescence is an optical phenomenon whereby the colours on a surface appear to change depending on the angle at which they're viewed or illuminated Iridescence is an optical phenomenon whereby the colours on a surface appear to change depending on the angle at which they're viewed or illuminated
Iron is a metallic chemical element which makes up about 5% of the Earth's crust. It's a very workable metal that's used extensively in industry. It's a lustrous material which is naturally magnetic although it can be demagnetized. The magnetic properties of iron have helped study the history of the Earth as ancient particles in rocks have aligned in different directions over thousands of years which reflect changes in the magnetic field of the Earth.
Iron is a very reactive metal which rusts easily, it's essential for both animal and human health and is also necessary for the health of plants. The vast majority of iron in our bodies is in our blood and iron rich blood cells carry oxygen around our body from our lungs.
The red, orange and yellow colours that can be seen in some soil and rocks is likely to be iron oxides and the inner core of the Earth is thought to be a solid iron-nickel alloy. Meteorites of iron and nickel are believed to be some of the earliest material which was formed soon after the formation of the universe. The red colouration of the planet Mars is known to be caused from iron oxides in its crust.
In industry almost all iron ore is used to make steel and one of the principle ores of iron is the mineral hematite.