Relevance of mineral texture on bidirectional reflectance and emission spectroscopy: Implications for geological remote sensing

This study evaluates the effect of grain-size, fabric, and composition of minerals on bidirectional reflectance and emission spectra. For this purpose, mineral grains of quartz (high albedo), feldspar (moderate albedo), and amphibole (low albedo) with four different grain-size ranges were analyzed using a goniometer system equipped with a spectroradiometer. Reflectance and emission spectra of bi-component mineral assemblages prearranged in seven different fabrics were analysed. It was observed that the parameters under investigation significantly influenced the intensity of reflection, scattering directions, spectral shape, and absorption depth, which in turn affected quantitative abundances estimated by techniques based on spectral similarity like Linear Mixture Model (LMM). It was observed that the error in abundances estimated by LMM varied from 3% to 15%. The authors conclude that the parameters under investigation, if neglected can introduce significant errors in geological interpretations.