Gaussian analysis of temperature effects on the reflectance spectra of mafic minerals in the 1‐μm region

Gaussian band‐fitting analysis has been applied to the reflectance spectra of mafic silicates, which are of geologic importance throughout much of the solar system. Reflectance spectra obtained over a sample temperature range of ≈80 to 448 K of olivine, clinopyroxene, and orthopyroxene were used in order to characterize the spectral changes in the 1‐μm wavelength region of these minerals as a function of temperature. Four Gaussians are required to characterize the olivine, while two Gaussians are necessary to characterize both the orthopyroxene and clinopyroxene. The trends of the individual Gaussian parameters (integrated area, width, and center position) are presented as a function of temperature for each mineral. The characterization by Gaussian analysis of the 1‐μm absorption feature of all minerals yields consistent trends in center position, integrated area, and width that may prove useful in quantitative determination of these minerals in mineral mixtures. The Gaussian analysis of olivine, for the three primary band components, is qualitatively consistent with previous crystal field transition assignments of Fe 2+ in the M(1) and M(2) crystallographic sites. The trends of the determined olivine Gaussian center positions imply that site symmetry is more important in determining transition energies than metal‐oxygen distances. The result of the Gaussian analysis for orthopyroxene is consistent with the need for two Gaussians to describe an asymmetric band. The Gaussian analysis of the clinopyroxene is consistent with previous assignments of crystal field transitions due to Fe 2+ in the M(1) and M(2) crystallographic sites.