Why does the type of mineral composition matter when identifying an igneous rock?
By looking at what type of mineral composition an igneous rock has you can determine what type of magma made it and what environment it was made in. What is the difference in composition between Felsic, Intermediate, Mafic, and Ultramafic igneous rocks? Igneous rocks contain the following common minerals: Plagioclase feldspar, Olivine, Potassium feldspar, Pyroxene, Quartz, Amphibole, Biotite, and Muscovite. The percentage of these minerals present in an igneous rock determines whether it is felsic, intermediate, mafic, or ultramafic. Felsic rocks are those that are light in color and are mostly made up of feldspars and silicates. Mafic rocks are darker colored and are mostly made up of magnesium and iron. Intermediate rocks fall somewhere in between being Felsic and Mafic. Ultramafic rocks are very dark colored. For more detailed descriptions of each type click on its name to be redirected to the glossary. What determines what type of texture an igneous rock has? Texture is determined
