Rocks are all around us, and most of them are small. But there are also many big ones, as well, and rocks are often millions of years old. There are three main different types of rocks:
Sedimentary, Metamorphic, and Igneous.
Sedimentary rocks form by water pushing down on sediment over time. Sediment can be anything organic, such as plants, sand, as well as dust. Sandstone and coal are some examples of Sedimentary rocks.
Igneous rocks form from molten rock (lava or magma) being cooled down to a certain temperature in which it hardens. 'Ignis' means 'fire' in Greek, so it fits the name.
When molten rock solidifies under the earth, for example, inside a volcano, it's called intrusive Igneous rocks. When molten rock solidifies outside the earth's surface, it's called extrusive Igneous rocks, and pumice and granite are examples of igneous rocks.
Metamorphic rocks form by different kinds of rocks heating and heating up under pressure. This process is called 'metamorphism', and is also usually made under the earth's surface, so it makes up 90% of the earth's crust. Some Sedimentary and Igneous rocks turn into metamorphic rocks when under pressure and heat. Slat is an example of Metamorphic rocks.
That's pretty much everything I know about the three different types of Rocks, and I hope you learned something while reading this!