Mafic lavas are hot, high in silica, low in volatiles, and relatively viscous. Volcanic lavas are called felsic lavas, and they are usually cooler and include high levels of silica and volatiles.

Rock analysis compilations show that rhyolite and granite are felsic rocks, while syenite, diorite, and monzonite are intermediate. Gabbro and basalt are mafic rocks, with an average silicon content ...