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.

---

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

---

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.

---

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.)

---

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

Among those technologies is direct air capture—in which carbon is absorbed from the atmosphere, enhanced rock weathering where rocks like basalt are spread over farm fields to capture dissolved carbon in rainwater.

From The Wall Street Journal • Jun. 17, 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

Iron was released from weathering basalt and carried underground by acidic groundwater.

From Science Daily • Apr. 23, 2026

The worst affected are the basalt columns that make up The Loom – 10 ft high leaning towers of rock.

From BBC • May 27, 2025

It was a dark gray basalt, and she used to hold it to her forehead, and it would immediately make her feel better: two and a half million years, right there against her skin.

From "A Place to Belong" by Cynthia Kadohata

Related Words

• magma
• slag