How Are Rocks Classified?

There are three kinds of rock: igneous, sedimentary, and metamorphic.

How Are Rocks Classified?

Rocks are a part of everyday life, used to build homes and line sidewalks. However, the rocks around us are not all the same.

Rocks are classified into three major categories: igneous, sedimentary, and metamorphic. Each type of rock has distinct characteristics that can be used to identify it.

Igneous rocks are formed when magma cools and solidifies. Magma is molten rock that is found deep within the Earth’s crust.

When it cools, it forms crystals and takes on a new shape. Igneous rocks can be classified based on their texture, which can range from fine–grained to coarse–grained.

Examples of igneous rocks include granite, basalt, and obsidian. Sedimentary rocks are formed when small pieces of sediment, such as sand or gravel, are compressed together over time.

These rocks often have layers and may contain fossils. Sedimentary rocks are classified by their composition, which can range from sandstone to limestone.

Metamorphic rocks are formed by the alteration of existing rocks due to intense pressure and heat. This process can cause the rocks to take on new shapes and textures. Metamorphic rocks are classified by their texture, which can