Modelling Reflectance Spectra of Muscovite as Function of Aluminium Content and Grain Size Using Hapke Model

Muscovite is an important mineral commonly found in hydrothermal systems of Earth and Mars. Reflectance spectra of muscovite has several diagnostic absorption features in wavelength range 0.4-2.5 µm. The absorption feature near 2.20 µm is sensitive to alumina content variations. In this study, we use reflectance spectra of powdered muscovite and geochemical datasets to quantify the relationship between spectral shift and alumina content. Imaginary index of refraction (k) was derived from reflectance spectra and a linear model was proposed relating alumina content and k. Reflectance spectra of muscovite was modelled for varying alumina content and grain size using Hapke model. Modelled spectra shows shift in wavelength position of 2.20 µm with varying alumina content and deepening of absorption features with increase in grain size. The results shall be helpful in interpretation of reflectance spectra acquired from space borne and airborne platforms.