Which type of rock forms from the cooling of molten rock?

Igneous rock forms from the cooling and solidification of molten rock, which can originate from magma beneath the Earth’s surface or from lava that erupts onto the surface during a volcanic event. When magma cools slowly underground, it creates intrusive igneous rocks, such as granite, which have large crystals due to the extended cooling time. Conversely, when lava cools quickly on the Earth's surface, it forms extrusive igneous rocks, such as basalt, which have small crystals because of the rapid cooling process.

The key characteristic of igneous rock formation is this direct relationship with molten material transitioning into a solid state, making it distinct from metamorphic rocks, which result from the transformation of existing rocks due to heat and pressure, or sedimentary rocks, which are formed from the accumulation and compaction of mineral and organic particles. Composite rock is not a recognized geological term, as rocks are generally categorized into three main types: igneous, metamorphic, and sedimentary.