Reference Terms
from Wikipedia, the free encyclopedia

Igneous rock

Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.

Note:   The above text is excerpted from the Wikipedia article "Igneous rock", which has been released under the GNU Free Documentation License.
Related Stories

Share This Page:

Science News
September 24, 2016

Latest Headlines
updated 12:56 pm ET