Delineating Blue-Dust Enriched Zones Within Banded Hematite Quartzite Using PRISMA Data: A Study in the Bolani Region, Odisha, India

Abstract

Blue dust, a high-grade martite-rich ore commonly found in conjunction with Banded Hematite Quartzite (BHQ) and Banded Hematite Jasper. It holds a distinctive stratigraphic position within Precambrian sedimentary iron ore deposits, and its formation is attributed to the supergene enrichment process. Blue dust, with higher Fe content compared to impure BHQ, is blended during mining with BHQ ore to elevate the Fe grade of low Fe₂O₃ BHQ ore. In this study, we utilized hyperspectral PRISMA data provided by the Italian Space Agency to identify blue dust zones within Banded Hematite Quartzite (BHQ) in the Bolani region of Odisha, India. The Bolani iron ore deposit is situated on the western limb of the renowned horseshoe-shaped Bonai-Keonjhar iron ore belt in Odisha, characterized by the presence of blue dust in fairly large pockets and lenses. Laboratory-generated spectral signatures revealed unique characteristics in blue dust, including a steeper slope in the spectral range from 1196 to 870 nm and greater absorption minima at 870 nm compared to BHQ samples. Leveraging these distinctions, a Relative Band Depth (RBD) image was generated, incorporating PRISMA bands aligned with the diagnostic spectral feature of blue dust observed at 733 nm and 1196 nm (for shoulders) and 870 nm (for absorption minima). A proposed composite image, combining RBD, the first Principal Component (PC-01) image derived from PRISMA bands within the 350–1350 nm spectral range, and a reflectance band at 1047 nm, effectively delineates blue dust zones from BHQ. Validation through field assessments, spectral signature comparisons, and mineralogical analysis of collected samples enhances the accuracy of the results. The findings of this study highlight the substantial potential of the PRISMA dataset for accurately delineating blue dust within BHQ, validating its effectiveness, and opening avenues for future research in optimizing mineral resource exploration.