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Time. The longer the crystals are allowed to grow, the bigger they get. Intrusive rocks cool slowly deep inside the earth, so they usually have larger crystals. These form from magma. Extrusive rocks cool very quickly since they are exposed to the atmosphere and hence have very small crystals. In fact obsidian (natural glass, volcanic glass) cools so quickly that it has only micro crystal. These are formed from lava.
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What would not be used to classify igneous rocks?
crystal size
Igneous rock are classified based upon their?
There are two types of igneous rocks; intrusive and extrusive. Intrusive igneous rocks are formed underneath the earth's surface from magma where it cools slower and develops large crystal structures. Extrusive igneous rocks are formed above the earth's surface from lava that cools quickly and creates rocks with smaller, finer crystal structures.
What conditions change igneous rocks and sedimentary rocks into metamorphic rocks?
Increased temperature and/or pressure.
Igneous rocks may be similar in mineral composition and yet have different?
Texture or crystal size.
What two conditions are necessary to form igneous rocks?
Increased temperatures and or decreased pressures.
What would not be used to classify igneous rocks?
crystal size
What relative cooling rates of igneous intrusive rocks can be estimated by comparing rocks?
Crystal
Igneous rock are classified based upon their?
There are two types of igneous rocks; intrusive and extrusive. Intrusive igneous rocks are formed underneath the earth's surface from magma where it cools slower and develops large crystal structures. Extrusive igneous rocks are formed above the earth's surface from lava that cools quickly and creates rocks with smaller, finer crystal structures.
What are porphyritic rocks?
Porphyritic Rocks are rocks that have big and small crystal's like the Igneous Rock "Andesite".
What conditions change igneous rocks and sedimentary rocks into metamorphic rocks?
Increased temperature and/or pressure.
What is the crystal size for extrusive igneous rocks?
Fine grained
Where are quartz crystal located?
Mainly within igneous rocks. Granite for example.
What is a factor that controls grain size in igneos rocks?
Crystal size in igneous rocks is controlled by the rate of cooling whereby the slower the rate, the larger the size of crystal.
What Evidence Would You Look For If Attempting To Classify A Piece of igneous Rock as Extrusive?
Extrusive igneous rocks have very small crystal grains.
Igneous rocks may be similar in mineral composition and yet have different?
Texture or crystal size.
What type of crystal are formed from in extrusive igneous rocks?
Small crystals, invisible without magnification.
Write the difference between extrusive and intrusive igneous rocks?
igneous Extrusive is cool on the outside of the crust and cools quickly before crystal forms igneous Intrusive is cool on the inside of the crust and cools slowly and allowing crystal to form
