How Igneous Rocks Are Formed

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** *How Igneous Rock Is Formed* **

 

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*Igneous rocks are called fire rocks and are formed either underground or
above ground. Underground, they are formed when the melted rock, called
magma, deep within the earth becomes trapped in small pockets. As these
pockets of magma cool slowly underground, the magma becomes igneous rocks.
*

*Igneous rocks are also formed when volcanoes erupt, causing the magma to
rise above the earth's surface. When magma appears above the earth, it is
called lava. Igneous rocks are formed as the lava cools above ground.*

For examples of igneous rocks, take a look at these:

*granite*

*scoria*

*pumice*

*obsidian*

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Source: www.fi.edu/fellows/fellow1/oct98/create/igneous.htm


how is igneous rock formed


Igneous rock - Wikipedia, the free encyclopedia

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** Igneous rock **

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Geologic provinces of the world (USGS)

  Shield
  Platform
  Orogen
  Basin
  Large igneous province
  Extended crust
Oceanic crust:
  0–20 Ma
  20–65 Ma
  >65 Ma

*Igneous rock* (derived from the Latin word /ignis/ meaning fire) is one of
the three main rock types, the others being sedimentary and metamorphic
rock. Igneous rock is formed through the cooling and solidification of
magma or lava. Igneous rock may form with or without crystallization,
either below the surface as intrusive (plutonic) rocks or on the surface as
extrusive (volcanic) rocks. This magma can be derived from partial melts of
pre-existing rocks in either a planet's mantle or crust. Typically, the
melting is caused by one or more of three processes: an increase in
temperature, a decrease in pressure, or a change in composition. Over 700
types of igneous rocks have been described, most of them having formed
beneath the surface of Earth's crust.

*Contents*

· 1 Geological significance
· 2 Morphology and setting

· 2.1 Intrusive
· 2.2 Extrusive
· 2.3 Hypabyssal

· 3 Classification

· 3.1 Texture
· 3.2 Chemical classification
· 3.3 History of classification

· 4 Mineralogical classification

· 4.1 Example of classification

· 5 Magma origination

· 5.1 Decompression
· 5.2 Effects of water and carbon dioxide
· 5.3 Temperature increase
· 5.4 Magma evolution

· 6 Etymology
· 7 See also
· 8 Notes
· 9 References
· 10 External links

*Geological significance[edit]*

Igneous and metamorphic rocks make up


Source: en.wikipedia.org/wiki/Igneous_rock

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