Rocks are mixtures of minerals. The Rock Cycle p rovides a framework that unifies the types of rocks as well as the processes that create rocks and transform them into each other. The rock cycle begins with m agma , a molten soup of minerals deep in the earth. Magma also contains dissolved gases. Lava is magma that has reached the earth s surface.
Minerals crystallize out at different temperatures.
Minerals react with remaining melt to produce the next mineral in the sequence. The mineral composition of an igneous rock is determined by the temperature of magma that the minerals crystallize from. Magma Temperature Mineral Composition Rock Classification Mineral Comp. Geologists invented words to describe the mineral compositions of various igneous rocks. But geologists applied a second naming scheme to igneous rocks, based on typical rocks of a given composition.