When lava reaches the surface of the Earth through volcanoes or through great fissures the rocks that are formed from the lava cooling and hardening are called extrusive igneous rocks. Some of the more common types of extrusive igneous rocks are lava rocks, cinders, pumice, obsidian , and volcanic ash and dust.
Rocks that form from within the earth (like through a volcanic eruption, lava flow, magma intrusion, etc.) are known as igneous rocks. ✔
