basalt

American  

[buh-sawlt, bas-awlt, bey-sawlt] / bəˈsɔlt, ˈbæs ɔlt, ˈbeɪ sɔlt /

noun

1. the dark, dense igneous rock of a lava flow or minor intrusion, composed essentially of labradorite and pyroxene and often displaying a columnar structure.

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basalt British  

/ ˈbæsɔːlt /

noun

1. a fine-grained dark basic igneous rock consisting of plagioclase feldspar, a pyroxene, and olivine: the most common volcanic rock and usually extrusive See flood basalt

2. a form of black unglazed pottery resembling basalt

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basalt Scientific  

/ bə-sôlt′,bā′sôlt′ /

1. A dark, fine-grained, igneous rock consisting mostly of plagioclase feldspar and pyroxene, and sometimes olivine. Basalt makes up most of the ocean floor and is the most common type of lava. It sometimes cools into characteristic hexagonal columns, as in the Giant's Causeway in Anterim, Northern Island. It is the fine-grained equivalent of gabbro.

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basalt Cultural  

1. A hard, dense igneous rock that makes up much of the material in tectonic plates. The part of the Earth's crust beneath the oceans consists mainly of basalt whereas continental crust consists mainly of less dense rocks, such as granite. (See plate tectonics.)

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Other Word Forms

• basaltic
  adjective
• basaltine
  adjective
• subbasaltic
  adjective

Etymology

Origin of basalt

1595–1605; < Latin basaltēs, a misreading, in manuscripts of Pliny, of basanītēs < Greek basanī́tēs ( líthos ) touchstone, equivalent to básan ( os ) touchstone (ultimately < Egyptian bh̬n ( w ) graywacke) + -ītēs -ite ¹

Compare meaning

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

• gabbro vs. basalt

Example Sentences

Instead of granite-like material, the data point to a surface made of basalt or mantle-like rock, similar to volcanic material found on Earth or the Moon.

From Science Daily • May 5, 2026

The 129-foot waterfall — a wide curtain of white water cascading from a basalt cliff face — generates its own rainbow and once was dubbed the “Eighth Wonder of the World” by President Theodore Roosevelt.

From Los Angeles Times • May 5, 2026

BOISE, Idaho—Each afternoon at around 4:30, the earth here shakes from a series of controlled explosions, as engineers blast through basalt bedrock to flatten out the ground underneath a gigantic new semiconductor factory.

From The Wall Street Journal • Feb. 17, 2026

They are a slightly lighter colour than the iconic hexagonal black basalt at the point of the causeway.

From BBC • May 27, 2025

The basalt highway led gradually downward, and after a while the slope increased, so the creatures could freewheel.

From "The Amber Spyglass" by Philip Pullman

Related Words

• magma
• slag