Volcanic (Extrusive) Rocks
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Volcanic (Extrusive) Rocks
Igneous rocks cool from melted material deep within the earth, called magma. Some magma makes its way to the surface (or very close to the surface) where it is exposed to surface temperatures. That means it cools quickly compared to magma that is more deeply buried.
Magma at the surface is called lava, and rocks that cool from lava are volcanic, extrusive, rocks. Of course, you knew that volcanic rocks come from volcanoes!
Volcanic rocks, because they cool so quickly, are fine-grained. That means you probably won't see a lot of individual mineral grains without a hand lens or even a microscope. Even though the rock is made of different mineral grains, it often looks like a pretty uninteresting, solid-color rock.
So if you know that a rock is igneous, and it seems to be all one color, call it a volcanic rock.
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