Iridium

What Is Iridium?

Iridium is a chemical element and one of the transition metals on the periodic table. Iridium appears as symbol Ir on the periodic table and has an atomic weight of 192.217 and a density of 22.56 g/cm³, making it the second-densest known element. Because iridium is so expensive, it is typically used only in applications that require a very small amount of the element.

Understanding Iridium

Iridium is the most corrosion-resistant metal on Earth. It is extremely difficult to melt, and because of its high melting point, it is hard to form, machine, or work iridium.

It is also one of the rarest elements in Earth's crust. The huge asteroid that many scientists believe wiped out the dinosaurs 65 million years ago is also believed to be responsible for the thin layer of iridium-rich clay found around Earth.

This layer of iridium forms the Cretaceous-Paleogene boundary (formerly known as the Cretaceous-Tertiary boundary). It is also known as the K-Pg boundary because the Cretaceous is represented by the letter K.

History of Iridium

The English chemist Smithson Tennant discovered iridium. He found the element in the residues from a solution of platinum ores in 1803. He named the metal Iridium after Iris, who was the personification of the rainbow in Greek mythology, because iridium salts are vibrant and multicolored. Because of its extremely high melting point, it wasn’t until 1842 that scientists could isolate it in a high-purity state. Iridium is also one of the rarest elements on earth, with gold being 40 times more common in the earth’s crust than iridium.

German chemist Rudolf Ludwig Mössbauer won the Nobel Prize in physics in 1961 for his research, using iridium, concerning the resonance absorption of gamma radiation, a phenomenon now called the Mössbauer effect.

Applications of Iridium

Iridium’s very high melting point makes it useful in many industrial applications, like the construction of high-grade spark plugs used in general aviation aircraft. Manufacturers also use it in the construction of crucibles, or containers for melting and manipulating other industrial metals. Iridium crucibles have most recently helped manufacture sapphire crystals, which require temperatures above 3,632 degrees F. Given that iridium’s melting point is 4,435 degrees F, pure iridium performs well at the temperatures required.

Manufacturers also combine iridium with osmium to make fountain pen nibs, and to construct pivot bearings and other scientific and specialized equipment.

Iridium has become an important component in the manufacture of LED screens and backlit displays of technology devices, such as iPads and iPhones. This has led to a surge in demand for the metal and sent its price skyrocketing. After Apple released its first iPad in 2010, iridium prices rose to over $1,000 per troy ounce. After a brief fall in 2013, iridium prices continued to rise, reaching an average price of $2,550 per troy ounce in 2020.

At $2,550 per troy ounce, iridium is more valuable than gold, silver, or platinum.

Iridium vs. Palladium

Many of iridium's industrial applications can be compared with palladium, a noble metal with properties similar to platinum. Both iridium and palladium have high melting points, high electrical conductivity, and extreme corrosion resistance, making both metals highly practical for electronics and industrial applications. Palladium is frequently used in catalytic converters, where it reacts with hydrocarbons in exhaust fumes. Iridium is often used in electronics because of its high tolerance to heat.

Example of Iridium

Due to its high electrical conductivity and resistance to corrosion at high temperatures, iridium is frequently used to tip spark plugs, the devices that ignite the fuel-air mixture in combustion engines.

Iridium is six times harder and eight times stronger than platinum, another precious metal used in high-grade spark plugs. Whereas copper spark plugs have an expected lifetime of 20,000 miles, those with platinum electrodes can last as long as 100,000 miles, and iridium spark plugs can last up to 25% longer than that. Iridium-tipped spark plugs are also more expensive, at a price point of eight to fifteen dollars per plug.

The Bottom Line

Iridium is a rare and valuable industrial metal with many applications in electronics and machinery. Recent innovations in mobile phone technology, combined with the widespread adoption of personal devices, have caused iridium prices to soar.

Iridium FAQs

What Color Is Iridium?

Iridium ore is white or gray, and when alloyed with other metals it is typically a shiny silvery-white color. Iridium salts have varied and vibrant colors.

Where Is Iridium Found?

Iridium is one of the rarest elements in the earth's crust. Iridium ores have been found in South Africa, the United States, Myanmar, Brazil, Russia, and Australia. South Africa is the leading producer of mined iridium.

How Is Iridium Ore Mined?

Pure iridium does not occur naturally. Iridium typically occurs in alloys with other noble metals, such as platinum. Iridium is usually produced as a byproduct of copper or nickel extraction.

How Much Does Iridium Cost?

In 2020, the average market price of iridium was $2,550 per troy ounce.