Basalt: A Brief Overview
Basalt is an extrusive igneous rock that is formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon. It is characterized by its low silica content, dark color, and high iron and magnesium content. Basalt is the most common volcanic rock type on Earth, making up over 90% of all volcanic rock on the planet.
Composition and Formation
- Basalt is composed of minerals including plagioclase feldspar, olivine, pyroxene, quartz, hornblende, and biotite.
- It is formed when magma rises onto the Earths surface, becoming lava, and then solidifies to form basalt rock.
- Basalt is usually dark grey to black in color, but can exhibit a wide range of shading due to its high content of augite or other dark-colored pyroxene minerals.
Distribution and Uses
- Basalt underlies more of Earths surface than any other rock type, and it is the bedrock of the ocean floor, occurring in extensive lava flows.
- It is used for a wide variety of purposes, including as an aggregate in construction projects, road base, concrete aggregate, asphalt pavement aggregate, railroad ballast, and filter stone in drain fields.
- Basalt is also cut into dimension stone, with thin slabs sometimes polished for use as floor tiles.
In summary, basalt is a significant rock type with various applications, and its formation and composition make it a valuable resource for construction and other industrial purposes.
