basalttikivestä

Basalt is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. It is typically fine-grained due to the rapid cooling of the lava, with crystals too small to be seen without a microscope. The texture of basalt is generally aphanitic or phaneritic. Basalt is characterized by its dark color, ranging from black to dark gray, and its high density. Its composition is primarily plagioclase feldspar and pyroxene, with smaller amounts of olivine and magnetite.

The formation of basalt is closely linked to volcanic activity. It is the most common rock type in the Earth's crust, particularly in oceanic crust, where it forms the vast plains of the ocean floor. Large igneous provinces, which are massive outpourings of basaltic lava, are also significant geological features. On other terrestrial planets and moons, basalt is also a prevalent rock type. For example, the dark plains on the Moon, known as lunar maria, are composed of basalt.

Basalt has numerous uses in human society. It is quarried for building materials, crushed for aggregate in road construction and concrete, and used in the manufacture of mineral wool for insulation. Its durability and availability make it a valuable resource. In some cultures, basalt has also been used for sculptures and decorative elements. The weathering of basalt can contribute to fertile soils due to the release of essential minerals.