What are extrusive igneous rocks?

Extrusive igneous rocks are indeed formed when lava cools and solidifies on the Earth's surface. This cooling process occurs relatively quickly when compared to intrusive igneous rocks, which form from magma that cools slowly beneath the surface. As lava erupts from a volcano and spreads out, it solidifies rapidly due to exposure to cooler air temperatures or contact with water. This rapid cooling usually results in a fine-grained texture, as the mineral crystals do not have as much time to grow.

This definition distinguishes extrusive rocks from other types of rocks, such as those formed from sediments or those that contain specific minerals like quartz. Additionally, the process of compaction and cementation of sediments leading to sedimentary rocks is separate from the processes that form igneous rocks. Understanding these distinctions highlights the dynamic nature of geological processes and the formation of different rock types.