An aphanitic (fine-grained) igneous rock is classified as basalt when its QAPF fraction is composed of less than 10% feldspathoid and less than 20% quartz, and plagioclase makes up …

The meaning of BASALT is a dark gray to black dense to fine-grained igneous rock that consists of basic plagioclase, augite, and usually magnetite.

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 …

basalt, extrusive igneous (volcanic) rock that is low in silica content, dark in colour, and comparatively rich in iron and magnesium. Some basalts are quite glassy (tachylytes), and …

Jan 28, 2026 · Basalt is the most abundant volcanic rock on Earth, covering more than 90% of the ocean floor and large continental regions shaped by ancient lava flows. It forms when mafic …

BASALT definition: the dark, dense igneous rock of a lava flow or minor intrusion, composed essentially of labradorite and pyroxene and often displaying a columnar structure. See …

Basalt is a fine-grained, dark-colored igneous rock that forms from the rapid cooling of lava at or near the Earth's surface. It is the most common type of volcanic rock and is primarily …

BASALT definition: 1. a type of black rock that comes from a volcano 2. a type of black rock that comes from a volcano…. Learn more.

Basalt is a type of black rock that is produced by volcanoes. The road snakes beneath mountains with basalt ramparts. Collins COBUILD Advanced Learner’s Dictionary. Copyright © …

A hard, dense, dark igneous rock composed chiefly of plagioclase feldspar, pyroxene, and olivine, and often having a glassy appearance. 2. A kind of hard unglazed pottery.