Iridium is a transition metal from the platinum group. Its chemical symbol is Ir with an atomic number of 77. It is the second densest metal next to Osmium. It was discovered by scientist Smithson Tennant in 1803 and named after the Greek goddess Iris. Being one of the rarest elements in the crust of the earth, iridium has been used to show a link between dinosaur extinction and impact craters. This was done by comparing the high metal occurrence found near the craters with chondritic meteorites and asteroids, which have a higher concentration than in the earth's crust.
Iridium was discovered in 1803 by Smithson Tennant. It was found in the residue of platinum ores. Even though Tennant is credited with its discovery, a few French chemists had also claimed credit to discovery the element. The name was chosen as Iris, personification of a rainbow, due to the diverse colors of its salts.
Iridium is part of the platinum group metals (PGMs). It is the second densest known metal. It has a silvery-white color resembling platinum and palladium. Its high hardness, brittleness, and high melting point (approximately 2500 degrees Celsius) make the metal difficult to work with or form. Most acids do not cause damage due to its high corrosion-resistance.
It occurs in nature uncombined, combined with platinum, or found in the natural alloys of osmiridium and iridosmine. Each is a different mixture of osmium and iridium. It is also a by-product of the nickel mining process.
Even though being one of the rarest elements in the earth, iridium does provide a good degree of functionality serving many purposes. Its use in spark plugs that is anti-corrosive and heat-resistant providing longer lasting and seemingly care-free plugs. Because of its higher melting temperature, compared to palladium and gold, these plugs can provide a better performance than other plugs except for some ruthenium alloys. It is also used in many objects such as in crucibles and other applications that require high temperatures, in electrical contacts, as a hardening agent for platinum, as a nib for fountain pens, and even jewelry.
Originally using a rhodium-containing catalyst, an iridium-containing catalyst has replaced rhodium for the production of acetic acid as part of the Cativa process. Ruthenium promoted iridium catalysts are superior to the rhodium-based system (Monsanto process). This switch has many benefits such as requiring a lowering the amount of water and reducing the number of drying agents in the process.
Historically, iridium was used a a tip material for fountain pen nibs and seen as a product of quality. Over time ruthenium, rhodium, osmium metals have now replaced it in pen nibs and has been labeled as "Genius Iridium". Its price or scarcity may be the reason for its now omission from pen nibs. An alternative to this label is gold. Gold provides a more flexible writing instrument over the more durable and lower prices of the other metals used in the former.
Prior to 2012 data has shown that demand for iridium worldwide was 300,000 ounces. Since 2012 demand has been halved but is trending upward. Russia and South Africa have the world's biggest deposits, with the latter having an export price value of about $350 million USD.
Prior to 2010 price data for iridium showed a steady price at just under $500 USD/oz. But, within the past few years there has been an increasing upward trend. This upward trend was seemingly similar to the prices of other PMGs, palladium and rhodium more specifically. In 2020, its price first passed the $2,000 USD/oz mark in the market. This is three times the prices seen prior to 2010. In 2021, the price of Iridium hit an all time high of more than $6,000 USD/oz. Gold, silver, and platinum group metals have been a commodity that investors look to for diversifying their portfolios. It is not listed on the London Metal Exchange.
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