Uses

Occurrence

Iridium is usually found with other metals from the platinum family.  It is mainly retrieved from northern Siberia, South Africa, Russia, pyroxinite deposits in Transvaal, nickel-copper ores in Canada, and Ural.  There are also smaller deposits in Colombia and Alaska.  Iridium is very rare on the earth making with a ratio of about 2 per billion occurrence but it is fairly common on iron meteorites about 3 per million occurrence and about .6 per million on stony meteorites.  This makes it possibly vital to understand dinosaur extinction because scientist can search for iridium in the earth's crust to find where meteorites impacted the earth.

Obtained

Iridium is obtained from platinum ores.  It is also a by product when mining nickel.  When found in platinum ores, it is an alloy or combination of metals and separating it is difficult.  One of the best ways to get the iridium from osmiridium is by first fusing it with zinc, then igniting the residue with barium nitrate.  Then boiling it with nitric acid, the iridium can then be precipitated from the solution by adding baryta (Barium hydroxide) and dissolved in aqua regia and then with the addition of ammonium chloride, it is precipitated as iridium ammonium.  Finally it is fused with nitre, water is added to take away the unwanted melt and the left over is fused with lead which is later removed with nitric acid and aqua regia to give you iridium.

How We Use It

Iridium is very useful for it its high melting and boiling point and its high density.  Also, because it is a transitional metal, it conducts electricity well.  Iridium is also considered the most corrosive resistant metal known meaning it does not react with high temperature, strong chemicals, acids, or bases making it ideal for objects that deal with such things.  Iridium is also considered not toxic because it does not have high reactivity with other elements making it easy to use but its compounds should be considered toxic.  It is used most often to mix into platinum alloys as a hardening agent.  It is often too brittle to be used by itself.  Iridium alloys are used for compass bearings because they of there high corrosive resistance which makes it last well in water.  It is also in crucibles because of its ability to withstand heat.  It is in similar devices to crucibles, as well as thermocouples which measures heat.  Spark plugs and other electrical contacts have iridium in them because of its ability to conduct electricity.  It is also used to treat cancer through high dose radiation therapy with its radioactive isotopes ability to release radiation.  Surgical instruments also often contain iridium because it makes them strong but it is dense so it does not take up a lot of space which is important when a surgeon has to keep their actions tiny.  It can also be found in polymer LED technology which is in computers and televisions because it conducts electricity and it strengthens without adding space.  It is also can be found in jewelry while it has a shiny appearance and will not react with anything a person is likely to come in contact with because it takes extremes for it to react at all.  Although the tip of a ballpoint pen is typically said to be made of iridium, this is no longer true as it was only in the early 20th century that iridium had this certain purpose.