Basalt is a fine-grained, dark-colored igneous rock composed mainly of plagioclase and pyroxene minerals. It is most commonly formed as extrusive rocks such as lava flow, but it can also form in small intrusive bodies such as a volcanic dike or a thin sill. Has a composition similar to gabbro. The difference between basalt and gabbro is that basalt is a fine-grained rock and gabbro is a coarse-grained rock.
