Some of the main minerals in igneous rocks are feldspar, quartz, olivine and mica. The size of the minerals depends on the depth of the magma that formed the rock. Deeper magma cools more slowly and forms larger crystals. read more
Types of Igneous Rocks The type of igneous rocks that form from magma is a function of three factors: the chemical composition of the magma; temperature of solidification; and the rate of cooling which influences the crystallization process. read more