Rocks that are formed from melted rock, usually by cooling:
Igneous Rocks
Igneous rock is one of the three main rock types:
1. igneous rock
2. metamorphic rock
3. sedimentary rock
The melted rock is called magma when it is below the surface, and lava when it flows out onto the surface. When the magma or lava cools or moves into areas of lower pressure, crystals or glass or both form. Thus, igneous rocks are composed of crystals, glass, or combinations of these materials.
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