A rock is any naturally occurring solid accumulation or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition and the gain entrance to which it is formed. Rocks are usually grouped into three main groups: igneous rocks, metamorphic rocks and sedimentary rocks. Rocks form the Earth’s outer unquestionable layer, the crust.
Igneous rocks are formed taking into account magma cools in the Earth’s crust, or lava cools on the arena surface or the seabed. The metamorphic rocks are formed taking into account existing rocks are subjected to such large pressures and temperatures that they are transformed—something that occurs, for example, when continental plates collide. The sedimentary rocks are formed by diagenesis or lithification of sediments, which in position are formed by the weathering, transport, and deposition of existing rocks.
The scientific psychiatry of rocks is called petrology, which is an indispensable component of geology.