Igneous

Descriptive of rocks or minerals formed by the cooling and solidification of magma or lava.

Part of speech: adjective
Definition: The term "igneous" pertains to one of the three main types of rocks, distinguished by being formed from solidified magma or lava. This process can occur either beneath the Earth's surface, resulting in intrusive (or plutonic) igneous rocks, or on the surface following volcanic eruptions, leading to extrusive (or volcanic) igneous rocks. The cooling rate of the magma or lava significantly impacts the size of the crystals that form within the rock, with slower cooling allowing for larger crystal growth. Igneous rocks are foundational in geology, providing critical insights into the Earth's composition and the processes that shape our planet. Their study is essential for understanding volcanic activities, tectonic movements, and the formation of Earth's crust.