A term qualifying the composition of igneous rocks, minerals, or magmas. Felsic rocks are light-colored reflecting their high content of silica-rich minerals (quartz, potassium feldspar, muscovite, and sodium-rich plagioclase feldspar). Consequentially, these rocks contain fewer iron and magnesium-rich (mafic) minerals (biotite, amphibole, pyroxene, olivine, and calcium-rich plagioclase feldspar).