On the stability of ferrous and ferric iron oxides and their role in rocks and rock-forming minerals stability

In physics, chemistry, metallurgy, and geochemistry, ferrous to ferric iron transformations are utilized. This transformation plays a crucial role in generating and preserving ferromagnetic properties by different chemical compounds. This paper investigates conditions for ferrous–ferric iron transformation and their role in the stability of iron-containing rocks and minerals. P-T conditions of this transformation strongly depend on temperature, pressure, oxidation conditions, and content of such elements as Mg, Ca, and Al. The transformation creates instability conditions for iron-containing rocks and minerals. Most high and ultra-high pressure metamorphic rocks and magmatic rocks may contain ferric iron only as a secondary component. This paper analyzes the stability of such essential rock-forming minerals as omphacite and biotite. The transition of ferrous iron to its ferric state has a significant role in forming and preserving ferromagnetic minerals and the transition of Cr (VI) to Cr (III). Some peculiarities in ferrous to ferric iron transformation should be taken into account in magnetic and paleomagnetic data interpreting.