What are igneous rocks?
Igneous rocks are rocks that are formed from minerals that have melted deep within the Earth.
Characteristics of igneous rocks:
-Formed when magma cools underground and crystalizes or when it erupt it erupts unto the surface of the ground, cools and crystallizes.
-*Intrusive: formed below the surface of the Earth.
-*Extrusive: formed on the surface of the Earth.
-Not in layers.
-With or without observable crystals.
-With or without air holes.
-Glossy or shiny.
-Hard.
-Course-grained.
*INTRUSIVE IGNEOUS
One type of igneous rock forms underground, within the Earth’s solid lithosphere, where magma cools slowly. This type of igneous rock has large crystals and it is called intrusive igneous rock.
*EXTRUSIVE IGNEOUS
Extrusive igneous rock forms above ground, where the magma cools quickly. Extrusive igneous rocks have small crystals.
Examples:
- pumice
- basalt
- andesite
- wehrlite
- monzonite
- anorthosite
- welded tuff
- nepheline syenite
- aplite
- websterite
- kimberlite
- gabbro
- diorite
- granite
- basanite
- troctolite
- pegmatite
- diabase
- obsidian
