Determination of modal composition of intimate mineral mixtures using bidirectional reflectance theory

Hapke reflectance theory is the most versatile method available for determining the modal mineralogy of a surface from reflectance spectra. This dissertation includes three projects which apply the theory in different ways to determine the modal mineralogy of the surface under investigation.; In the first project, Hapke theory is fit to the laboratory spectra of intimate mixtures of Corning glasses. The single scattering albedo of the mixture is calculated from the optical constants of the glasses, instead of from single scattering albedos derived from fits to the end member spectra. The abundances determined are very close to the known mixture abundances. This technique eliminates the dependence of the end member single scattering albedos on the grain sizes of the samples from which they were measured.; In the second project, Hapke theory is used to calculate mixture series of common lunar minerals. These mixture series can be used to derive calibrations for interpreting lunar telescopic spectra. The most significant outcome of this project is the realization that Hapke theory offers a tool for studying any mixture series without extensive laboratory work. If spectra of the end members are available, any mixture series desired can be easily calculated. This technique can be used to gain insight into complex spectra of real surfaces.; In the third project, Hapke theory is fit to the spectrum of the asteroid Vesta to determine the modal mineralogy. The abundances determined were very similar to those determined for Vesta by analogy to the mineralogy of the eucrite meteorites. This is particularly significant, because spectra of meteorite mineral separates were not available, therefore the fit was made using the closest minerals available, and much of the necessary information had to be assumed.