Question #751c2
2 Answers
Explanation:
Igneous rocks are formed when magma cools and they are separated into two categories: The plutonic rocks and the volcanic rocks. The first is formed when underground magma cools and solidifies. Two more specific types (out of about 700 types) of rocks are: The Extrusive which forms at the earth's crust after a volcanic eruption and it is the result of the lava rapidly cooling and the Intrusive kind (the most known is Basalt) which is formed in underground chambers, caves or tunnels forming mineral crystals due to the slow cooling of the magma.
When magma cools, it forms an igneous rock.
There are two kinds of igneous rock: intrusive and extrusive .
Explanation:
When magma cools below ground, it takes longer, and the minerals in it have time to cool and separate into identifiable little crystals.
These are the Intrusive igneous rocks.
Examples are granite , diorite and gabbro.
Magma that cools above ground cools much faster, and the individual minerals in it don't have time to separate out into easily-visible crystals - the crystals in it are very fine.
These rocks are called Extrusive igneous rocks.
Example of these are basalt , andesite and rhyolite.
Obsidian is an extreme example of an extrusive igneous rock. It cools so quickly, it's basically a glass.
If a volcanic eruption is very explosive and the lava is thrown up into the air, it solidifies and falls to the ground in different-sized pieces called pyroclastics or tephra.
