Geology is the study of rocks and minerals. The study of rocks of minerals can help miners to learn where the rocks they are looking for can be found. The study of rocks and the formation of the rocks can also tell people about the way that the land was formed. Geologists can tell a lot about what happened by studying the layers of rock that make up the earth’s crust. There are three different types of rocks: igneous, sedimentary, and metamorphic. You can use this rock identification table from About.com’s guide to Geology. If you are looking for lesson plans on rocks, check these plans from teAchnology.com.
Igneous rocks are formed directly from magma. Magma is the melted rock that is found below the earth’s surface. Igneous rocks may be formed when a volcano erupts, and the magma reaches the earth’s surface. Igneous rocks can also be formed when the magma cools underground.
Pictures of Igneous Rocks from Geology.com
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Identification Table for Igneous Rocks
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Sedimentary rocks are formed by pressing the layers of debris and rock material together over time. Sedimentary rocks can show a true picture of the changes of the environment over time. You can see examples of sedimentary deposits in many cliff walls, as the lines of color that go through the rock walls.
Metamorphic rocks are rocks that have changed over time. They usually begin as igneous or sedimentary rocks, but through heat and pressure the composition of the rock has changed. Examples of metamorphic rocks are marble and quartzite.
Minerals are different from rocks because they are a specific chemical composition. Rocks can have several different minerals inside of them. Minerals follow specific atomic structures and have distinctive properties that depend on the type of mineral that you find. Common minerals are salts, coal, gold, and mica.