Chapter 4, Problem 1RQ

To determine

The similarity and contrast between the freezing of magma and the freezing of water.

Answer to Problem 1RQ

Magma and water crystallizes when the suitable temperature is attained. But magma can crystallize at various temperatures as different compounds, where as water crystallizes at a particular temperature without any compositional change. Hence, they differ.

Explanation of Solution

Magma is the molten rock that is present deep inside the surface. When it reaches the surface it is called as lava. Magma, when cooled at certain pressure and temperature, it crystallizes and forms rocks of different compositions at different depths.

Water when kept at $0°\text{C}$ starts crystallizing. If the temperature is maintained as such, all the water converts to form ice. The same happens with magma. When the temperature is suitable for crystallization process, they start crystallizing. This crystallizing phenomenon is complex in this case because of the presence of multiple compounds in the magma.

As a result of various compounds present, all the crystals formed are not of same composition. Different crystals are formed at different temperatures. Thus, the early formed rocks are maffic whereas the later formed rocks are felsic. This process is known as Fractional Crystallization.