Basalt (UK: / ˈbæsɒlt, - ɔːlt, - əlt /; [1][2] US: / bəˈsɔːlt, ˈbeɪsɔːlt /) [3] is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low- viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt ...
Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill.
Learn how basalt forms from mantle magma, its mineral composition, types, and global significance in Earth’s crust and volcanic provinces.
Basalt, extrusive igneous (volcanic) rock that is low in silica content, dark in color, and comparatively rich in iron and magnesium. Basalts may be broadly classified on a chemical and petrographic basis into two main groups: the tholeiitic and the alkali basalts. Learn more about basalt in this article.
Basalt is the most common type of volcanic rock found on Earth. It is typically dark in color and is commonly vesicular, and has either an aphanitic or porphyritic texture. Basalt most often occurs as lava flows that travel great distances or as lava pillows formed in subaqueous eruptions. Scoria and cinders also usually have basaltic compositions.
Basalt: Composition, Properties, Types, Uses Basalt constitutes the Earth's most abundant igneous rock type, estimated to comprise approximately 70% of the planet's crust. What is Basalt Basalt is defined as a fine-grained, dark-colored igneous rock composed mainly of plagioclase and pyroxene minerals, with or without olivine.