  The absorption features of olivine in visible and near-infrared (VNIR)
reflectance spectra are the key spectral parameters in its mineralogical
studies. Generally, these spectral parameters can be obtained by exploiting the
Modified Gaussian Model (MGM) with a proper continuum removal. However,
different continua may change the deconvolution results of these parameters.
This paper investigates the diagnostic spectral features of olivine with
diverse chemical compositions. Four different continuum removal methods with
MGM for getting the deconvolution results are presented and the regression
equations for predicting the Mg-number (Fo#) are introduced. The results show
that different continua superimposed on the mineral absorption features will
make the absorption center shift, as well as the obvious alterations in shape,
width, and strength of the absorption band. Additionally, it is also found that
the logarithm of a second-order polynomial continuum can match the overall
shape of the spectrum in logarithmic space, and the improved regression
equations applied to estimate the chemical composition of olivine-dominated
spectra also have a better performance. As an application example, the improved
approach is applied to pulse laser irradiated olivine grains to simulate and
study the space weathering effects on olivine diagnostic spectral features. The
experiments confirm that space weathering can make the absorption band center
shift toward longer wavelength. Therefore, the Fo# estimated from remote
sensing spectra may be less than its actual chemical composition. These results
may provide valuable information for revealing the difference between the
spectra of olivine grains and olivine-dominated asteroids.
