Plutonite

Geology, which is part of the geosciences, deals with the composition and structure of the earth's crust (earth = grch. Ge), its physical properties and its history of development as well as the processes that shape it. Mineralogy deals with the individual, sometimes microscopically small components of rocks, the minerals. Palaeontology deals with the fossil content (fossilised remains of plants or animals) of sedimentary rocks. Each rock in the earth's crust can be assigned to one of the three major rock classes based on its specific formation (microstructure, structure). Each of these can be transformed into a rock of the other two by geological processes (rock cycle):

• Magmatites: crystalline or solidified rocks
• Sediments: layered rocks
• Metamorphites: metamorphic or remodelled rocks

Magmatites - crystalline or solidified rocks

Magmatites are formed by cooling and solidification. They are categorised into plutonites (deep rocks) and volcanites (effusive rocks) according to their solidification depth. Plutonites are formed when rising magma slowly cools long before reaching the earth's surface and mineralises in large crystals.

Common crystalline deep rocks are granite, mica schist and gneiss. When molten magma cools, hard, dense solidification rocks such as basalt or obsidian are formed. In the case of volcanites, liquid magma erupts as lava on the earth's surface to cool in water or in the air. Gas-filled tuff rocks are formed from...