Here's why:
* Iron and Mafic Magma: Iron is a major constituent of mafic magma. Mafic magmas are characterized by high levels of magnesium (Mg) and iron (Fe), along with relatively lower levels of silica (SiO2).
* Crystallization and Composition: When minerals containing significant amounts of iron crystallize, they remove iron from the remaining magma. This leaves the magma enriched in the remaining elements, particularly silica. As silica content increases, the magma transitions from mafic (basalt) to intermediate (andesite) and eventually felsic (rhyolite).
* Example: Consider olivine, a common mineral in mafic rocks. Olivine contains a significant amount of iron. As olivine crystallizes from mafic magma, it removes iron, leading to a slight increase in the silica content of the remaining magma.
Therefore, the magma remaining after crystallization of iron-rich minerals would likely be mafic, but with slightly higher silica content than the original magma.
