What are the two main types of igneous rock?

Igneous rocks are classified primarily into two categories based on where the molten rock cools and solidifies: intrusive and extrusive. Intrusive igneous rocks, also known as plutonic rocks, form from magma that cools slowly beneath the Earth's surface, allowing large crystals to form. Examples include granite and diorite. On the other hand, extrusive igneous rocks, or volcanic rocks, form from lava that cools quickly on the Earth's surface, resulting in smaller crystals. Common examples of extrusive rocks include basalt and pumice.

The distinction between these types is fundamental to understanding the processes involved in rock formation and the geological characteristics of different igneous rocks. The formation environment leads to different textures, mineral compositions, and appearances between intrusive and extrusive rocks.