magma

American  

[mag-muh] / ˈmæg mə /

noun

plural

magmas, magmata

1. Geology. molten material beneath or within the earth's crust, from which igneous rock is formed.

2. any crude mixture of finely divided mineral or organic matter.

3. Chemistry, Pharmacology. a paste composed of solid and liquid matter.

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magma British  

/ ˈmæɡmə, mæɡˈmætɪk /

noun

1. a paste or suspension consisting of a finely divided solid dispersed in a liquid

2. hot molten rock, usually formed in the earth's upper mantle, some of which finds its way into the crust and onto the earth's surface, where it solidifies to form igneous rock

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magma Scientific  

/ măg′mə /

1. The molten rock material that originates under the Earth's crust and forms igneous rock when it has cooled. When magma cools and solidifies beneath the Earth's surface, it forms what are known as intrusive rocks. When it reaches the Earth's surface, it flows out as lava and forms extrusive (or volcanic) rocks.

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magma Cultural  

1. Molten rock usually located deep within the mantle of the Earth that occasionally comes to the surface through cracks in the mantle or through the eruption of volcano es.

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Usage

What’s the difference between magma and lava? Magma is what molten (melted) rock is called when it’s under the earth’s surface. Lava is what molten rock is called when it flows out of a volcano or volcanic vent. To be clear, in popular use, magma and lava are essentially different names for the same liquid-hot, charred orange ooze—which name is used depends on whether it is above or below the surface. However, geologists and volcanologists have their reasons for using the two different terms to distinguish between forms of what is the same substance. Magma doesn’t always become lava—sometimes it cools and solidifies beneath the earth's surface. Sometimes, it collects in what’s known as a magma chamber. When it does reach the surface, it flows out as lava. The rock that’s formed when it hardens and cools can also be called lava, though this use of the term is uncommon outside of technical, scientific contexts. The word lava is perhaps the more well-known of the two because that’s the one we see when volcanoes erupt (or when the floor turns into it). Here is an example of magma and lava used correctly in the same sentence. Example: Lava began flowing from the volcano three days after scientists detected movement of magma underground. Want to learn more? Read the full breakdown of the difference between magma and lava.

Discover More

When magma cools and solidifies, it forms igneous rock, of which lava is one type.

Other Word Forms

• magmatic
  adjective
• magmatism
  noun

Etymology

Origin of magma

1400–50; late Middle English < Latin: dregs, leavings < Greek mágma kneaded mass, salve, equivalent to mag- (base of mássein to knead, press; see mass) + -ma noun suffix of result

Explanation

That red hot liquid rock that spews violently out of erupting volcanoes? That's lava. But before the lava rises to the earth's surface it's called magma. Although lava and magma are often used interchangeably, technically magma is the name for the hot molten rock (mixed with gases and mineral crystals) that collects in chambers beneath the Earth's crust. Once the magma breaks through the Earth's surface and flows down the volcano, you can call it lava. There are about 1500 active volcanoes on the Earth and at least 80 under the oceans — which add up to a lot of magma and possible lava.

Example Sentences

"This would be a secondary atmosphere that is continuously replenished by the magma ocean. Magma is not just crystals and liquid rock; there's a lot of dissolved gas in it, too."

From Science Daily • May 8, 2024

Magma from that blast has been found in Greenland, some 4,500 km away.

From Reuters • Oct. 5, 2023

That’s a lot for a town still clawing back economically after the Magma copper mine first shut down in 1982, later opened for a few years, then closed for good in 1996.

From Seattle Times • Jun. 29, 2023

Magma continues to erupt from the northeast rift zone, spurting upward in red fountains, and scientists are unsure what might come next.

From New York Times • Dec. 3, 2022

Magma, mag′ma, n. any soft doughy mass: the molten mass within the earth's crust: the residuum after expressing the juice from fruits.

From Chambers's Twentieth Century Dictionary (part 2 of 4: E-M) by Various

Related Words

• basalt
• slag