Optical constants of synthetic potassium, sodium, and hydronium jarosite

摘要: The hydroxy sulfate jarosite [(K,Na,H 3 O)Fe (SO 4 ) 2 (OH) 6 ] has both been discovered on Mars, and is associated with areas of highly acidic runoff Earth. Because extremely sensitive to formation conditions, it an important target mineral for remote sensing applications. Yet at visible near infrared (VNIR) wavelengths, where many spacecraft spectrometers collect data, the spectral abundance a in mixture not linearly correlated surface that mineral. Radiative transfer modeling can be used extract quantitative estimates if optical constants (the real imaginary indices refraction, n k all minerals are known. Unfortunately, wide variety minerals, including sulfates like jarosite, available. This due, part, inherent difficulty obtaining such data tend crystallize naturally as fine-grained (~10 μm) powders, jarosite. However, powders obtained by inverting equation radiative using model laboratory spectra. In this paper, we provide robust synthetic potassium, hydronium, sodium VNIR. We also explicitly describe calculation procedures (including access our Matlab code) so others may obtain additional minerals. Expansion library VNIR will facilitate extraction abundances, leading more in-depth evaluations locations.