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

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Compare meaning

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

• cobalt vs. royal blue

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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

See Examples For:

cobalt

Deep-sea mining seeks to tap previously untouched seabed deposits of a range of commodities, including cobalt and nickel, but the fledgling industry has long been stalled by environmental concerns.

From Barron's ● Aug. 25, 2026

Cuba holds significant deposits of cobalt and nickel, which are used in the production of electronics.

From Salon ● Aug. 21, 2026

At the same time, the carbon support kept the platinum cobalt nanoparticles smaller than 5 nanometers and prevented them from becoming unevenly distributed.

From Science Daily ● Aug. 8, 2026

Deep-sea mining companies want to scour the ocean's abyssal plains for mineral deposits and polymetallic nodules laden with nickel, copper and cobalt.

From Barron's ● Aug. 6, 2026

A few bright stars lingered in the cobalt sky.

From "A Dance with Dragons" by George R. R. Martin

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Related Words

• blue-green

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