Geologist Norman L. Bowen showed that if crystals in basaltic magma were ejected upward from the magma before the crystals reacts with the magma, it will crystallize into another type of igneous crystal. He showed that igneous rocks will change if they are at a lower temperature they are unstable at. These reactions are part of a series of reactions called Bowen’s Reaction Series.The basaltic reactions can be split into the continuous and the discontinuous reactions. The continuous series includes calcium rich plagioclase crystallizing into sodium rich plagioclase. The discontinuous reaction series includes the crystals reacting a bit with the magma before crystallizing. Olivine can form within magma. If the magma is allowed to cool a bit, olivine will react with the magma, turning it into
A picture of Bowen’s Reaction Series
pyroxene. This continues until the rock is biotite. The continuous series describes plagioclase feldspar evolving from calcium-rich to sodium-rich.
At the point the two series meet, alkali feldspars such as orthoclase form. Orthoclase becomes muscovite, or potash mica. Finally, at the end of the line, the muscovite becomes quartz, one of the most common rocks on Earth.