Rocks

 A rock is a naturally formed, non-living material. It is made up of collections of mineral grains that are held together in a firm, solid mass as a result of multiple geological processes. 

Minerals are substances that are formed naturally on the Earth. They are usually solid, inorganic, have a definite crystal structure, and are formed naturally by continuous geological processes. 

Elements are chemically the simplest substances on Earth and hence cannot be broken down further even by chemical reactions. 

Most of the Earth's rock started off as igneous rock, through the cooling and solidification of magma or lava. The rate of cooling of magma affects the size of crystals found in the rock.

Granite is used widely in contructing buildings. It is a coarse-grained igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground.

Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill.

Gabbro is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges.

Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO₄ silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO₂. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar.

Metamorphic rocks arise from the transformation of existing rock to new types of rock, in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than 150 to 200 °C (300 to 400 °F) and, often, elevated pressure (100 megapascals (1,000 bar) or more), causing profound physical or chemical changes.

Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding.