Vulcanite

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. The term was first used in 1778 by the Swiss meteorologist Jean-André Deluc (1727-1817); before that, geognosy was commonly used. General geology deals with the forces acting on the earth's body and the processes that contribute to the formation of rocks on a large scale. 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 solidification rocks
• Sediments: layered rocks
• Metamorphites: metamorphic or remodelled rocks

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.

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. The most common crystalline deep rocks are granite,...