Which type of rock is formed from the rapid cooling of magma at the Earth's surface?

Extrusive igneous rock is formed from the rapid cooling of magma that reaches the Earth's surface, resulting in solidification before it can crystallize into larger mineral grains. When magma erupts from a volcano or flows as lava, the cooling occurs quickly due to exposure to the atmosphere or water, leading to a fine-grained texture. This process can also produce volcanic glass, such as obsidian, and other features like volcanic ash.

In contrast, intrusive igneous rocks form from magma that cools slowly beneath the Earth's surface, allowing larger crystals to form. Metamorphic rocks arise from the alteration of existing rocks under heat and pressure, while sedimentary rocks form from the accumulation and lithification of sediments. Understanding these processes is fundamental in geology, as it illustrates how different rock types are formed based on their cooling rates and environments of formation.