irid·​i·​um | \ i-ˈri-dē-əm How to pronounce iridium (audio) \

Definition of iridium

: a rare silver-white hard brittle very heavy metallic element — see Chemical Elements Table

Examples of iridium in a Sentence

Recent Examples on the Web The Census Bureau’s count for other precious metals includes silver, platinum, palladium and more obscure sources such as ruthenium and iridium. Dian Zhang, USA TODAY, 3 Mar. 2021 Analyzing the concentration of rare earth elements in the sediments, Alvarez discovered the famous iridium anomaly. David Bressan, Forbes, 24 Feb. 2021 Within seconds the gas streaming around the plummeting probe will reach temperatures hot enough to melt its aluminum chassis, followed by the iridium cladding that shields its plutonium power source. Lee Billings, Scientific American, 14 Sep. 2017 Rare in the crust of the Earth, iridium is common in meteorites, suggesting that this layer was deposited after a major impact about 65 million years ago at the boundary between the Cretaceous and Tertiary geologic periods. Smithsonian Magazine, Smithsonian Magazine, 22 Apr. 2020 In 1980, the father and son team of Luis and Walter Alvarez, digging into a roadcut outside the town of Gubbio, Italy, discovered a layer of rock enriched in the element iridium. Smithsonian Magazine, Smithsonian Magazine, 22 Apr. 2020 In October 2019, a study was published that said a brief ice age period occurred roughly 12,800 years ago and was caused by an asteroid impact, after researchers found high levels of iridium and platinum in White Pond near Elgin, S.C. Fox News, 12 Mar. 2020 Rather than basing the kilogram off of an object—a platinum-iridium alloy cylinder about the size of a golf ball—the new definition uses a constant of nature to set the unit of mass. Jay Bennett, Smithsonian Magazine, 6 May 2012 Precious metals like platinum and iridium were needed to boost efficiency, making a cheaper catalyst crucial. David Grossman, Popular Mechanics, 24 Oct. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'iridium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of iridium

1804, in the meaning defined above

History and Etymology for iridium

Greek īrid-, îris "rainbow, iridescent halo around the moon, a flame, etc., iris entry 1" + New Latin -ium -ium; from the colors produced by dissolving it in hydrochloric acid

Note: The word iridium was introduced by the English chemist Smithson Tennant (1761-1815) in Philosophical Transactions of the Royal Society, 1804, Part II, p. 414: "As it is necessary to give some name to bodies which have not been known before, and most convenient to indicate by it some characteristic property, I should incline to call this metal Iridium, from the striking variety of colours which it gives, while dissolving in marine acid." See also osmium.

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The first known use of iridium was in 1804

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Cite this Entry

“Iridium.” Dictionary, Merriam-Webster, Accessed 13 Jun. 2021.

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More Definitions for iridium


irid·​i·​um | \ i-ˈri-dē-əm How to pronounce iridium (audio) \

Kids Definition of iridium

: a hard brittle heavy metallic chemical element


irid·​i·​um | \ ir-ˈid-ē-əm How to pronounce iridium (audio) \

Medical Definition of iridium

: a silver-white hard brittle very heavy metallic element of the platinum group used especially in hardening platinum for alloys (as for surgical instruments) symbol Ir — see Chemical Elements Table

More from Merriam-Webster on iridium

Nglish: Translation of iridium for Spanish Speakers Encyclopedia article about iridium


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