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 at least 65% of its …

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 …

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 magma, …

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 chemical and …

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 lava exposed …

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

Definition: Basalt is a fine-grained, dark-colored igneous rock composed mainly of plagioclase feldspar and pyroxene minerals. It forms from the rapid cooling of mafic (low silica) lava at or near Earth's …

Basalt is a hard, black volcanic rock with less than about 52 weight percent silica (SiO2). Because of basalt's low silica content, it has a low viscosity (resistance to flow). Therefore, basaltic lava can flow …

Venus, Mars, the Moon, and some of the largest asteroids had volcanoes that produced basalt. Only about 0.9% of all meteorites are basalts but about 16% of those meteorites known as achondrites …