Basalt is an extrusive igneous rock, meaning it forms from the rapid cooling and solidification of lava at or near Earth's surface

. It is fine-grained (aphanitic) and typically dark in color, ranging from black to dark gray, due to its high content of iron and magnesium minerals such as pyroxene, plagioclase feldspar, and olivine

. Basalt is classified as a mafic rock because it has relatively low silica content (about 45-52%) and is rich in magnesium and iron

. It is the most common volcanic rock on Earth, making up over 90% of all volcanic rocks and a large portion of the oceanic crust

. There are different types of basalt based on composition and mineralogy, including:

• Tholeiitic basalt: the most common type, rich in iron and calcium-poor pyroxene, common in oceanic crust and volcanic mountain belts

• Alkali basalt: richer in sodium and potassium, often found in continental rift zones and volcanic islands

• Other types include olivine basalt, clinopyroxene basalt, and plagioclase basalt, depending on dominant minerals

Basalt is known for its hardness (around 5-6 on the Mohs scale), durability, and resistance to weathering, making it widely used in construction and other industries

. In summary, basalt is a fine-grained, dark-colored, mafic extrusive igneous rock formed from rapidly cooled lava, primarily composed of plagioclase feldspar, pyroxene, and olivine