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Contributor: Hannah Brooks. Lesson ID: 12451
If you see an animal, you can usually tell what kind of animal it is. An elephant is not the same as a mouse, and a bird is unlike a beetle. Rocks are different, too, so learn how to identify them!
If you have stone, brick, marble, tile, sand, glass, or even metal in your house, you have some type of rock!
Explore those plain old rocks in your yard and learn how to tell what kind is what!
Rocks can be found in many places in nature.
They are under our feet, used to build homes and make up the roads we drive along. These rocks are classified based on how they form. There are three types of rocks: igneous, sedimentary, and metamorphic.
Igneous rocks are formed when magma from under the earth’s surface cools and solidifies. Igneous rocks can form above or below the ground.
Since they are created from magma, they often have tiny bubbles or holes that result from air in the rock as it cools. These rocks usually look the same all the way around.
Some have large particles in the rock, like granite, but many do not have visible particles.
Igneous rocks can also be glassy, like obsidian, pictured below.
Sedimentary rocks form when sediment builds up in an area. Think about how dust settles on untouched surfaces in your house.
Sedimentary rock forms similarly, with layers forming on top of one another. Sometimes, you can even see the layers in the rock.
Other sedimentary rocks do not have layers you can see, but you can feel large pieces of material in the rock.
These rocks are usually pretty soft and break apart easily.
Metamorphic rocks have been exposed to high amounts of heat and intense pressure.
It might change shape! Metamorphic rocks do the same thing!
If a metamorphic rock forms from a sedimentary rock, you might be able to see the layers, even after the heat and pressure.
Rocks can change into other types of stone by moving through the rock cycle. Rocks are constantly being recycled into new substances.
As rocks break apart, they move as sediment, eventually becoming sedimentary rocks. Once buried, they may be exposed to heat and pressure, changing into metamorphic rock.
So you see, the characteristics of each type of rock are based on how they form on the earth.
Test your knowledge in the Got It? section with a drag-and-drop interactive.
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