What are most igneous rocks primarily composed of?

Igneous rocks are mostly made up of silicate minerals. These silicates are of two types, light and dark silicates. The dark silicates are also called ferromagnesian because of the presence of iron and magnesium in them. They include olivine, pyroxene, amphibole and biotite. The light-colored silicates include quartz, muscovite and feldspar.

You can learn more about igneous rocks when you check the link.