A series of articles on the different elements. The Lego blocks with which we, our earth and the matter of the universe are built all have their own specific properties. In this series we go through each element step by step and we look at some useful things the wikipedia has to say about it, along with an interesting video of the University of Nottingham with which various experiments are done with the element in question.
Today number 77 of the 118 elements, Iridium (Ir).
Iridium is mainly used in alloys where the hardness of the material is important. Other uses are:
- Crucibles and other equipment that must withstand high temperatures.
- Electrical contacts such as Pt / Ir-spark plugs
- The points of fountain pens and compass needles.
From 1889 until 1960 was the definition of the meters the distance between two notches on a bar consisting of one alloy of platinum and iridium, the so-called X-meter, stored in Sèvres, France. Later this was replaced by another definition (see krypton).
Iridium is difficult to work with because it is very hard and brittle. It is a silvery white metal with a slight yellow sheen. Iridium is the most resistant to corrosion of all metals acids (even against aqua regia). With some melted sodium-salts like NaCl(table salt) and NaCN, however, iridium does react.
Iridium is found in an unbound state in the earth's crust, often in combination with other metals from the platinum group. In addition, it occurs in the natural alloy iridiosmium. The core of the earth is rich in iridium and in places it rises to the surface. Most commercially mined iridium is produced as a byproduct of the copper mining.