Magma and Lava Composition

Magma is the molten rock underlying a volcano and is made up of these ten elements:

            Oxygen

            Silicon

            Aluminum

            Iron

            Magnesium

            Titanium

            Calcium

            Sodium

            Potassium

            Phosphorus

Magma is made up of predominantly oxygen and silicon, making it easy to classify types of magma by the amount of silica (SiO2) in their composition.

Mafic magmas have less silica and a larger amount of Fe and Mg. Having less silica, they are less thick and more gases can escape.

Felsic magmas have comparatively more silica and lower quantities of Fe and Mg.  Having more silica, they are thicker and hold in more gases.

Lava is the magma when it comes to the surface, cools and hardens into rock.

Most lava is basaltic, which is lava that forms from mafic magmas. 

            -Lower viscosity because of lower silica content (less solid)

            -Usually comes in less explosive eruptions.

Lava of dactite and rhyolite types is formed from felsic magmas.

            -Higher viscosity because of a higher silica content (less liquidity)

            -Tends to accompany more explosive eruptions.

Andestite lava is created by magma containing an intermediate amount of silica.