What is the difference between an Extrusive and Intrusive igneous rock?
The difference between an Extrusive and Intrusive igneous rock is the way in which they cool. An Extrusive igneous rock cools very fast on the surface and is created by lava. Since the cooling process is very fast extrusive igneous rocks have very small crystals (fine grained). On the other hand an Intrusive igneous rock cools very slowly beneath the surface and is created by magma. Since the cooling process is very slow intrusive igneous rocks have very large crystals (coarse grained). In some instances there is also a third type of igneous rock. Technically it is an extrusive rock, but it resembles glass. This glass type of igneous rock forms when magma/lava is instantly cooled. What are the properties used to identify Igneous rocks? Properties used to identify igneous rocks include mineral composition, texture, and color. There are four different mineral compositions; Felsic, Intermediate, Mafic, and Ultramafic. The texture of an igneous rock is determined by its grain size. There a