Igneous Rock Cycle Igneous rocks are formed as magma from below the earth’s crust cools and hardens.

Igneous Rock Formation Cooling may occur deep beneath the earth’s crust forming intrusive igneous rock. Cooling may be rapid at or near the surface forming extrusive igneous rocks.

Igneous Rock Formation Slow cooling produces rocks with large grains. Intrusive: large grains. Fast cooling produces smaller, often unnoticeable grains. Extrusive: smaller grains Rocks can begin to cool slowly and then rapid cool Porphyry: combo grains

Families of Igneous Rocks Felsic rocks are formed from magma called felsic – high in silica (SiO2) Mafic rocks are formed from mafic magma – low in silica Ultramafic rocks are made up of a combination of the minerals in both felsic and mafic magma.