Spectral and chemical characterization of Copiapite and Rozenite from Padinjarathara in Wayanad, southern India: Possible implications for Mars Exploration 04/01/2025

Earth and Space Sciences

Copiapite (Fe2+Fe3+4(SO4)6(OH)2·20 H2O) and rozenite (Fe2+(SO4)· 4H2O) are secondary hydrous sulfate minerals, mostly formed because of oxygenation and weathering events of primary sulfides on Earth. These secondary sulfate minerals are significant in defining past geological environments on Earth and other rocky planets such as Mars. We discuss here the results of chemical and spectral analyses of copiapite and rozenite found in massive sulfide zones associated with banded iron formations (BIFs) in the Wayanad region in Kerala, southern India. The results from different spectroscopic techniques -VNIR reflectance, TIR (emitted radiation), FTIR, Laser Raman, and X-ray diffraction-were recorded and matched with existing literature and databases. The genesis of copiapite and rozenite in the area is through seasonal and temporary development of an acidic environment, with the high elevations of the Wayanad plateau providing the necessary low-humidity condition during the dry season. Copiapite and rozenite were detected as alteration products in different regions on Mars, which can provide insights into environmental conditions that prevailed during the biogeochemical evolution of Mars. The study of copiapite and rozenite formation in a terrestrial environment will therefore enhance our understanding of similar mineral precipitation, genesis, and fluvial processes on Mars. Future missions to Mars could also use the data obtained from the present study to calibrate similar instruments to detect these secondary sulfate minerals.

Field photographs of A) Gossan (high oxidation) developed over the massive sulfide zone in the study area, the whitish encrustations are mainly rozenite (secondary hydrated iron sulfate). B) Oxidized zone showing the weathered rock with purple – to maroon garnet and white-colored rozenite. C and D) Rozenite (white) and Copiapite (yellow) developed as encrustations and coating over the partly oxidized massive sulfides.

(a) Volcanogenic origin of primary sulfides. (b) Precipitation of secondary sulfate minerals by myriad processes like oxidation, hydrolysis, and evaporation.