Q:

What are some facts about rocks?

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Quick Answer

Rock is the primary component of the Earth's crust. Although soil, sand and other natural materials are similar to rocks, they are not actually rocks and are classified as derivatives of rocks. Minerals are necessary to form nearly all types of rock, and most include more than one mineral. Metals are also found in many rock types.

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Full Answer

There are three classes of rock and they are all formed in different ways. Igneous rock is created by the cooling of a molten mixture of minerals called magma. Magma is found below the earth's crust. When the magma cools below the Earth's surface, the rocks that are formed are called intrusive, and when it cools above the Earth's surface, they are extrusive rocks.

Sedimentary rock is created from loose material, such as sand, pebbles, mud and even pieces of organic matter. Sediments are loose materials that are moved from one place to another. Sediment becomes rock after millions of years of pressure and chemical action.

The final type of rock is metamorphic rock, which forms under the Earth's surface through the alteration of existing sedimentary or igneous rocks. These alterations can be caused by pressure, chemical reactions, movement of the Earth's crust, heat and pressure.

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Related Questions

  • Q:

    What are metamorphic rocks?

    A:

    Metamorphic rocks are formed when the properties of existing igneous or sedimentary rocks are altered by contact with heat or pressure. They are typically found deep underground where the conditions necessary for their formation exist.

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  • Q:

    Where do rocks come from?

    A:

    Rocks come from magma, which is the molten material found within the earth. When magma cools, either above or below the earth's surface, it crystallizes and forms the igneous rocks that can later be changed into metamorphic or sedimentary rocks. Magma, which can be considered molten rock, is referred to as lava when it reaches the earth's surface.

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  • Q:

    What are the similarities and differences between rocks and minerals?

    A:

    Rocks and minerals are inorganic compounds and occur throughout the world but have distinct physical characteristics, distinguishing features and societal uses that set them apart. Minerals are generally lighter in weight and color than rocks and hold value for their aesthetic properties. Rocks, in contrast, are denser, darker and hardier and find use in the industrial and construction industries.

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  • Q:

    How do rocks form?

    A:

    Rocks are formed in three primary ways, and each method produces rocks with different characteristics. Rocks are either classified as sedimentary, igneous or metamorphic, depending on the manner in which they were formed. Most rocks encountered in everyday life are sedimentary, although some igneous rocks, such as granite, are also common.

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