MgFe

MgFe is a shorthand used in different scientific contexts to refer to the combined presence or ratio of magnesium (Mg) and iron (Fe). It is not a single distinct compound, but a descriptor applied to compositions, indices, or systems where Mg and Fe play central roles.

In geology and mineralogy, Mg and Fe define a major part of many silicate minerals. A well-known example is the olivine solid solution, spanning forsterite (Mg-rich) to fayalite (Fe-rich). Describing a mineral’s composition along this Mg–Fe axis helps explain variations in density, melting behavior, and crystallization. The concept also underpins the broader Mg–Fe ratios used to characterize meteoritic and planetary materials.

In astronomy, MgFe appears as a spectroscopic index that combines magnesium and iron absorption features in a star's or galaxy’s spectrum. A common definition is MgFe = sqrt(Mgb × <Fe>), where Mgb is the Mg b line strength and <Fe> is the average of the Fe5270 and Fe5335 indices. This composite index aims to trace total metallicity while reducing sensitivity to the detailed [Mg/Fe] or [α/Fe] abundance ratios. A related variant, MgFe’, is used to minimize certain abundance effects further.

In materials science, the Mg–Fe system is studied for lightweight metal applications and related intermetallics. The exact phases and properties depend on composition and processing; magnesium can be alloyed with iron to tailor strength, density, and corrosion resistance for specific applications.

Overall, MgFe serves as a versatile shorthand reflecting the interplay of magnesium and iron across disciplines, rather than a single chemical substance.