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 …

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 …

Apr 10, 2018 · 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 …

Dec 20, 2025 · 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 …

Aug 17, 2023 · Basalt is a common and widely used, fine-grained, dark-colored mafic volcanic rock. It has mainly calcic plagioclase feldspar and augite.

Basalt is defined as a fine-grained, dark-colored igneous rock composed mainly of plagioclase and pyroxene minerals, with or without olivine. It is formed from the rapid cooling of basaltic …

Dec 14, 2012 · Discover basalt—the most common volcanic rock: composition, textures, and its role in Earth's crust and ocean floors.

Basalt is a dark-colored, fine-grained igneous rock that forms from the rapid cooling of mafic lava. It is the most common extrusive rock on Earth, making up most of the ocean floor and many …

1 day ago · basalt (countable and uncountable, plural basalts) (mineralogy) A hard mafic igneous rock of varied mineral content; volcanic in origin, which makes up much of the Earth's oceanic …

Basalt and related rock types like andesite and dacite are rocks that form when volcanoes erupt magma (lava) onto the surface of the earth and the magma cools. Basalt flows on Hawaii.