30+ Interesting Facts About Rocks
A rock is a natural solid mass of one or more minerals. It is the primary unit of the Earth’s outer layers: crust and mantle. The core, on the other hand, consists of iron (85%) and nickel (15%). There are three major classes of rocks , categorized by their formation: igneous, sedimentary, and metamorphic rocks. They are further divided into various groups and types based on their chemical, mineralogical, and textural differences. Igneous rocks are formed either within the Earth (magma that solidifies underground) or with lava spewed from volcanoes and solidifying on the surface. Common examples are granite, basalt, and pumice. Sedimentary rocks are formed from layers of sand, silt, animal skeletons, and dead plants. Some common types are shale, chalk, sandstone, and banded iron. Metamorphic rocks are the result of changes in existing underground rocks. These changes occur due to the impact of temperature, pressure, or chemicals. Widely known rocks include marble (a metamorphosed limes...