The prospects for mineral analysis by remote infrared spectroscopy.
An investigation of the effects of physical parameters on the spectra of minerals has been carried out, and an attempt made to develop a comprehensive theory of the reflectance (or emittance) spectra of particulate surfaces. The theory involves the effects of particle size, surface roughness, porosity, and mixing ratios on the spectra of mineralogical assemblages. The true spectral information is represented by the refractive indices and absorption coefficients of the constituent minerals. The present theory and the Mie theory for a cloud of well separated quartz particles are compared, as well as theoretical and experimental reflectances of quartz powders, glass beads, and corundum powders. Experimental results of abrading sapphire are presented.