1. Igneous Rocks: Formed from the cooling and solidification of magma (molten rock) or lava.
* Extrusive igneous rocks: Formed from lava that erupts on the surface, like basalt and rhyolite.
* Intrusive igneous rocks: Formed from magma that cools beneath the surface, like granite and gabbro.
2. Sedimentary Rocks: Formed from the accumulation and cementation of sediments, like sand, mud, and shells.
* Clastic sedimentary rocks: Formed from fragments of other rocks, like sandstone and shale.
* Chemical sedimentary rocks: Formed by precipitation of minerals from water, like limestone and rock salt.
* Organic sedimentary rocks: Formed from the accumulation of organic matter, like coal and oil shale.
3. Metamorphic Rocks: Formed when existing rocks are transformed by heat, pressure, or chemical reactions.
* Foliated metamorphic rocks: Have a layered or banded appearance, like slate, schist, and gneiss.
* Non-foliated metamorphic rocks: Lack a layered appearance, like marble and quartzite.
The crust is also composed of various minerals, which are the building blocks of rocks. Some common minerals found in the crust include:
* Quartz
* Feldspar
* Mica
* Amphibole
* Pyroxene
The crust is divided into two main types:
* Oceanic crust: Thinner and denser, primarily composed of basalt and gabbro.
* Continental crust: Thicker and less dense, with a more diverse composition including granite, sedimentary rocks, and metamorphic rocks.
It's important to note that the specific composition of the crust varies depending on its location and geological history.
