Light colored igneous rock is called felsic, it is high in quartz, muscovite mica, and orthoclase feldspar content. Dark colored igneous rock is called mafic, and contains a lesser amount of silica along with olivine, pyroxene, amphibole, biotite mica, and plagioclase feldspa
Light coloured igneous rocks (felsic) tend to have greater silica and aluminum content and a lower iron and magnesium content than dark (mafic) rocks.