Question:
What is an igneous rock? Describe the method of formation
and characteristics of igneous rock.
Answer:
Igneous rocks are formed from magma and lava. That is why it is also called primary rocks. Igneous rocks can be formed in the earth's crust or on the surface.
Example of igneous rocks,
- Granito, Gabbro, Pegmatite, basalt, volcanic breccia, and tuff.
The following are three methods of formation and characteristics of igneous rock:
- At great depth, the magma cooled very slowly, as a result, mineral grains may be very large.
- At the earth's surface, the lava cooled very fast, as a result, minerals grains become smooth and small.
- At the shallower depth, the magma cools neither very slow nor very fast, as a result, igneous grains become intermediate size neither larger nor smaller.
Since igneous rock is the primary rock that is formed from magma directly, hence fossils are not found in them.
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