noun \bə-ˈslt, ˈbā-ˌ\

: a type of dark gray to black rock

Full Definition of BASALT

:  a dark gray to black dense to fine-grained igneous rock that consists of basic plagioclase, augite, and usually magnetite
ba·sal·tic \bə-ˈsl-tik\ adjective

Origin of BASALT

Latin basaltes, manuscript variant of basanites touchstone, from Greek basanitēs (lithos), from basanos touchstone, from Egyptian bḫnw
First Known Use: 1601

Other Geology Terms

anthracite, boulder, cwm, erratic, igneous, intrusive, mesa, sedimentary, silt, swale


noun    (Concise Encyclopedia)

Dark igneous rock that is low in silica content and comparatively rich in iron and magnesium. Some basalts are glassy (have no visible crystals), and many are very fine-grained and compact. Basaltic lavas may be spongy or pumice-like. Olivine and augite are the most common minerals in basalts; plagioclase is also present. Basalts may be broadly classified into two main groups. Calc-alkali basalts predominate among the lavas of mountain belts; the active volcanoes of Mauna Loa and Kilauea in Hawaii erupt calc-alkali lavas. Alkali basalts predominate among the lavas of the ocean basins and are also common in mountain belts.


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