- the dark, dense igneous rock of a lava flow or minor intrusion, composed essentially of labradorite and pyroxene and often displaying a columnar structure.
Origin of basalt
- a fine-grained dark basic igneous rock consisting of plagioclase feldspar, a pyroxene, and olivine: the most common volcanic rock and usually extrusiveSee flood basalt
- a form of black unglazed pottery resembling basalt
Word Origin and History for basalt's
c.1600, from Late Latin basaltes, misspelling of Latin basanites "very hard stone," from Greek basanites "a species of slate used to test gold," from basanos "touchstone." Not connected with salt. Said by Pliny ["Historia," 36.58] to be an African word, perhaps Egyptian bauhan "slate." Any hard, very dark rock would do as a touchstone; the assayer compared the streak left by the alleged gold with that of real gold or baser metals. Hence Greek basanizein "to be put to the test, examined closely, cross-examined, to be put to torture."
- 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.