Question

What is basalt?

Answer 1

Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a planet or moon. More than 90% of all volcanic rock on Earth is basalt.

a dark fine-grained volcanic rock that sometimes displays a columnar structure, typically composed largely of plagioclase with pyroxene and olivine.