Intrusive igneous rocks, also known as plutonic rocks, are formed when magma cools and solidifies beneath the Earth’s surface. This process occurs slowly, allowing the minerals within the magma to crystallize and form larger, well-defined crystals.
As magma rises from deeper within the Earth, it can accumulate in pockets or chambers before it eventually cools down. The cooling process can take millions of years, resulting in the formation of rocks like granite, diorite, and gabbro. These rocks often exhibit a coarse-grained texture due to the larger crystal sizes, which are a direct result of the extended cooling time compared to extrusive igneous rocks, which form from lava cooling quickly at the surface.
Factors such as the composition of the magma, the depth at which it cools, and the surrounding rock materials can influence the characteristics and mineral composition of the resulting intrusive igneous rock.