Rocks are the natural occurring substance containing of one or more minerals. Rocks form the Earth’s outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere.
Rocks are categorized used 3 types.
1. Igneous rocks- Also known ad magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava.
Igneous rocks occur in a wide range of geological settings: shields, platforms, orogens, basins, large igneous provinces, extended crust and oceanic crust. Igneous rocks are classified according to mode of occurrence, texture, mineralogy, chemical composition, and the geometry of the igneous body. There are relatively few minerals that are important in the formation of common igneous rocks, because the magma from which the minerals crystallize is rich in only certain elements: silicon, oxygen, aluminium, sodium, potassium, calcium, iron, and magnesium. These are the elements that combine to form the silicate minerals, which account for over ninety percent of all igneous rocks.
2. Sedimentary rocks- These are the types of rock that are formed by the accumulation or deposition of mineral or organic particles at the Earth’s surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place.
3. Metamorphic rocks:Metamorphic rocks make up a large part of the Earth’s crust and form 12% of the Earth’s land surface.They are classified by their protolith,their chemical and mineral makeup, and their texture. They may be formed simply by being deeply buried beneath the Earth’s surface, where they are subject to high temperatures and the great pressure of the rock layers above. They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction and distortion.