cobalt

American  

[koh-bawlt] / ˈkoʊ bɔlt /

noun

1. a silver-white metallic element with a faint pinkish tinge, occurring in compounds whose silicates afford important blue coloring substances for ceramics. Co; 58.933; 27; 8.9 at 20°C.

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cobalt British  

/ ˈkəʊbɔːlt /

noun

1. a brittle hard silvery-white element that is a ferromagnetic metal: occurs principally in cobaltite and smaltite and is widely used in alloys. The radioisotope cobalt-60 , with a half-life of 5.3 years, is used in radiotherapy and as a tracer. Symbol: Co; atomic no: 27; atomic wt: 58.93320; valency: 2 or 3; relative density: 8.9; melting pt: 1495°C; boiling pt: 2928°C

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cobalt Scientific  

/ kō′bôlt′ /

1. A silvery-white, hard, brittle metallic element that occurs widely in metal ores. It is used to make magnetic alloys, heat-resistant alloys, and blue pigment for ceramics and glass. Atomic number 27; atomic weight 58.9332; melting point 1,495°C; boiling point 2,900°C; specific gravity 8.9; valence 2, 3.

2. See Periodic Table

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Etymology

Origin of cobalt

1675–85; < German Kobalt, variant of Kobold kobold

Compare meaning

How does cobalt compare to similar and commonly confused words? Explore the most common comparisons:

• cobalt vs. royal blue

Explanation

Cobalt is a silvery-gray metal. It's also the name of a deep blue pigment that's made from cobalt. Cobalt, mined from the earth's crust along with copper and nickel, has a shiny appearance with a slightly bluish tint. Chemically combining cobalt with aluminum oxide results in the blue pigment that's been familiar to artists for centuries. Cobalt blue is the blue in very old Chinese blue-and-white porcelain, and it features in paintings by Monet and van Gogh. Cobalt is from the German kobold, "household goblin," a nickname miners gave arsenic-laced ore that made them sick.

Example Sentences

A more stable environment might make it easier to develop Libya’s vast resources of rare earths and other critical minerals, which include uranium and potentially lithium and cobalt.

From The Wall Street Journal • Apr. 15, 2026

The US is also negotiating a minerals deal with DR Congo to help gain access to the central African country's vast reserves of key metals such as cobalt, tantalum, lithium and copper.

From BBC • Apr. 6, 2026

Over more than a decade, Chinese companies, willing to take on significant risks, have spent billions of dollars buying up mines in Congo, which produces nearly 75% of the world’s cobalt.

From The Wall Street Journal • Mar. 31, 2026

China currently dominates the global supply of lithium and cobalt, both of which are needed in batteries.

From Barron's • Mar. 28, 2026

Wiping cookie crumbs from his mustache, he turned into the main road, and there, outlined in cobalt blue, stood Guitar.

From "Song of Solomon" by Toni Morrison

Related Words

• blue-green