alumina

American  

[uh-loo-muh-nuh] / əˈlu mə nə /

noun

1. the natural or synthetic oxide of aluminum, Al 2 O 3 , occurring in nature in a pure crystal form as corundum.

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alumina British  

/ əˈluːmɪnə /

noun

1. another name for aluminium oxide

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alumina Scientific  

/ ə-lo̅o̅′mə-nə /

1. Any of several forms of aluminum oxide used in aluminum production and in abrasives, refractories, ceramics, and electrical insulation. Alumina occurs naturally as the mineral corundum and, with minor traces of chromium and cobalt, as the minerals ruby and sapphire, respectively. In its hydrated form it also occurs as the rock bauxite. Also called aluminum oxide. Chemical formula: Al ₂ O ₃ .

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Etymology

Origin of alumina

1780–90; < Latin alūmin-, stem of alūmen alum ¹ + -a ⁴

Compare meaning

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

• alumina vs. aluminum

Example Sentences

Smelters are trucking in raw materials to keep operating, but analysts say that can’t match the volume of alumina and other products that typically come in via the waterway.

From The Wall Street Journal • May 29, 2026

Smelters dissolve refined bauxite, or alumina, in a solution and jolt it with an electric current to chemically separate the aluminum from oxygen.

From The Wall Street Journal • Apr. 12, 2026

It mines bauxite, the raw material for aluminum, refines it into alumina powder, and operates smelters that turn alumina to finished aluminum.

From Barron's • Mar. 30, 2026

Morgan analyst William Peterson wrote in a recent note to clients that roughly a third of Alcoa’s alumina capacity is contracted to “key players” in the Middle East, including EGA and Alba.

From MarketWatch • Mar. 30, 2026

Aluminium and oxygen form alumina, of which are constituted the sapphire, the ruby and other precious stones, but alumina is most commonly found in combination with silica, or silicon and oxygen.

From Marvels of Scientific Invention An Interesting Account in Non-technical Language of the Invention of Guns, Torpedoes, Submarine Mines, Up-to-date Smelting, Freezing, Colour Photography, and many other recent Discoveries of Science by Corbin, Thomas W.