iridium powder is one of the rarest and most expensive industrial metals on earth. Its price fluctuates with production, demand, speculation and hoarding, which makes it an extremely volatile asset to hold on to.
Iridium is a silvery-white metallic element with an atomic number of 77. It is chemically similar to platinum but has a higher melting point, and is more resistant to corrosion than pure platinum.
Discovered by Smithson Tennant in 1803 and named after the Greek goddess of iris, iridium is a member of the platinum group of metals. It is very hard and brittle, with a high specific electrical resistivity at 0degC (edged out by osmium for both properties) as well as having a very high melting point.
Aside from its applications as a hardening agent for platinum, iridium has numerous other uses, including fountain pen nibs (alloyed with osmium), compass bearings, high-temperature crucibles and heavy-duty electrical contacts. It also serves as an alloying element to produce gold-iridium alloys, which are much harder and stiffer than pure platinum.
Some iridium is mined from copper and nickel ores, which are extracted in a wet process using a mixture of aqua regia and nitric acid. The residuals of this process are then smelted and refined to produce iridium products, which have excellent thermal and mechanical properties.
Iridium is not affected by acids, bases or most other strong chemicals. It is therefore a good material for making objects that will be exposed to these substances. It is also used in particle physics for the production of antiprotons, which are the particles that make up antimatter.