* Mafic: Rich in magnesium and iron (hence the name "mafic," from magnesium and ferric). This gives it a dark color, typically black or dark gray.

* Extrusive: It formed from lava that erupted onto the Earth's surface, as opposed to intrusive rocks that solidify underground.

Here's a more detailed breakdown:

Composition:

* Primarily composed of pyroxene and plagioclase feldspar.

* May contain small amounts of olivine and amphibole.

* Generally has a low silica content, typically 45-55%.

Texture:

* Fine-grained: The rapid cooling of lava on the surface prevents large crystals from forming.

* Aphanitic: Individual crystals are too small to be seen without a microscope.

* May contain phenocrysts: Larger crystals that are visible to the naked eye.

* Often exhibits a vesicular texture: Tiny holes or cavities formed by escaping gas bubbles during the cooling process.

Formation:

* Formed from the eruption of basaltic magma, which is relatively fluid and commonly found in shield volcanoes and oceanic ridges.

* Found in a variety of settings, including:

* Oceanic crust: The majority of the Earth's oceanic crust is made of basalt.

* Continental flood basalts: Massive outpourings of basalt that cover large areas of continents.

* Mid-ocean ridges: Basalt forms along the divergent plate boundaries where new crust is created.

Uses:

* Construction material: Basalt is used as aggregate in concrete and asphalt.

* Decorative stone: Basalt is used for paving stones, building facades, and sculptures.

* Industrial applications: Basalt fibers are used in composites, insulation, and other industrial applications.

In short, basalt is a dark, fine-grained, extrusive rock that is common in volcanic areas and forms the foundation of much of the Earth's oceanic crust.