Rock types

Rocks are solid materials made up of minerals, forming the Earth's crust. They are classified into three main types based on how they form: igneous (from cooled magma or lava), sedimentary (from pressed layers of mineral particles or fossils), and metamorphic (original rocks transformed by heat and pressure). Igneous rocks like granite are often hard and crystalline, sedimentary rocks like sandstone can contain fossils or layered structures, and metamorphic rocks like slate have a foliated, dense texture. Understanding rock types helps reveal Earth's history and processes shaping its surface.