<p>Spinel is a key mineral in magmatic systems, preserving signatures of their formation tectonic environments. However, processes like fluid-rock interactions and regional metamorphism can significantly alter their original chemical composition and microtexture. Chloritization is a process where primary spinel can react with surrounding silicates in the presence of H₂O and SiO₂-rich fluids in a reducing environment, leading to the formation of Cr- and Fe²⁺-rich ferrous chromite and pores filled with chlorite. While chloritization under reducing conditions is well known, its formation in oxidizing environments is undocumented. In the Archean Somnavandlapalli Ultramafic-Mafic (UM-M) Complex, disseminated Cr-spinels in ultramafic rocks are completely transformed with their primary composition erased, recording their chemical evolution in the progressive oxidizing environment. The Cr-spinel exhibit two distinct textures: clean (inclusion-free) and chloritized porous spinel with chlorite-filled cavities. Both display systematic zoning with core-rim texture, from a modified altered core with ferrian chromite (RIM-I) and Cr-magnetite (RIM-II) formed during progressive hydrothermal alteration under oxidizing conditions. Oxidation-induced chloritization and forming Fe³⁺-rich and Cr-depleted ferrian chromite (RIM-I) without ferrous chromite, followed by chlorite dissolution and magnetite precipitation, leads to the development of Cr-magnetite (Rim-II). Subsequent re-equilibration and homogenization resulted in the distinct zoning patterns in spinel grains. Final martitization converted magnetite to hematite, marking the terminal stage of the spinel alteration in a progressively oxidizing environment.</p>