Abstarct: The indicator mineral method is one of the effective approaches in geochemical exploration, involving the identification of heavy minerals, the assessment of mineralization presence or absence, and the determination of vectors toward ore centers. In volcanogenic massive sulfide (VMS) deposits, chlorite is an important indicator mineral that typically concentrates in the footwall zones. The Vanakan barite–baxse mextal deposit, located 23 km northeast of Semnan, is a bimodal-felsic (Kuroko-type) VMS deposit hosted in Eocene volcano-sedimentary units, which is investigated in this study. Mineralogical, chemical, and structural characteristics of chlorite were examined in hydrothermal alteration zones near the ore body (B) and distal to it (C) using energy-dispersive X-ray spectroscopy (EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and Raman spectroscopy analyses. In alteration zone B, Mg-rich chlorites with smaller crystallite sizes are dominant, whereas in zone C, Fe-rich chlorites with larger crystallite sizes prevail. Raman spectroscopy confirmed that chlorites in zone B are Mg-rich, while those in zone C are Fe–Mg-rich. The AI and CCPI indices indicate stronger alteration in zone B compared to zone C. Comparison of the Vanakan deposit with six other VMS deposits of different types in Iran reveals that proximal chlorites in higher-temperature systems are Fe-rich with larger crystallite sizes, whereas in lower-temperature systems they are Mg-rich with smaller crystallite sizes. The alteration zoning model in the Vanakan deposit evolves from Fe-rich chlorite (distal) to Mg-rich chlorite (proximal) and finally to silicic–chloritic alteration at the center. The results of this study demonstrate that the chemical and structural characteristics of chlorite can serve as reliable exploration vectors toward ore centers and play an effective role in identifying mineralization zones within VMS systems.