Visible to near-infrared optical properties of pure synthetic olivine across the olivine solid solution

Abstract

Olivine exhibits highly diagnostic absorption features across visible to near-infrared (VNIR) wavelengths due to electronic transitions of Fe 2+ in its crystal structure. The properties of these absorptions vary with composition, enabling compositional analysis of olivine through VNIR spectroscopy, both in the laboratory and through remote sensing. Previous analyses of these trends have relied on natural olivine samples, which are influenced by the presence of minor cations that can affect the diagnostic absorptions. We conduct a systematic analysis of a suite of synthetic (pure Mg/Fe) olivine samples with VNIR (300-2600 nm) reflectance spectroscopy and quantitative spectral deconvolutions. From the full suite of samples described and characterized by Dyar et al. (2009), we identify a small suite of well-characterized and chemically pure olivine samples that demonstrates consistent and reliable spectral reflectance properties across visible to near-infrared wavelengths. This suite covers the stoichiometric olivine solid solution from x = Mg/(Mg+Fe) = 0 to x = 70 (Fo 0 to Fo 70 ). Because of their tight compositional control, these synthetic samples improve on previous analyses of natural samples. The results of this study provide a new standard for spectral reflectance properties of olivine across visible to near-infrared wavelengths for the compositions present in the suite. We present updated data on the trends in olivine band position as a function of olivine composition, which are the basis for remote compositional evaluation of olivine with visible to near-infrared reflectance spectroscopy. For these reasons, these improved olivine band position trends are of major importance to remote compositional analyses of terrestrial planets.

Olivine‐Carbonate Mineralogy of the Jezero Crater Region

“…Our approach to mapping olivine composition is in some ways related to previous studies of the olivine composition of the Moon using continuum removed M 3 data (Isaacson et al, 2011) and follow-on laboratory studies of synthetic olivine samples (Isaacson et al, 2014). These studies have established the ability of continuum removed VNIR spectra to determine the relative Fe versus Mg composition from orbit and then checked their results using the MGM approach (Sunshine & Pieters, 1998).…”

Constraints on olivine‐rich rock types on the Moon as observed by Diviner and M3: Implications for the formation of the lunar crust

“…Olivine is identified at VNIR wavelengths by three overlapping Fe 2+ bands near 1.1 μm whose positions shift slightly with composition or Fo# (=100 × MgO/ (MgO + FeO t )) [Sunshine and Pieters, 1998;Dyar et al, 2009;Isaacson et al, 2014]. Pyroxene exhibits two sets of Fe 2+ bands: one shortward of 1 μm, centered near 0.9 μm for low-Ca pyroxene and shifting to longer wavelengths with increasing Ca content [Adams and McCord, 1972;Klima et al, 2008Klima et al, , 2011, and one at 2 μm.…”

Identification of Potential Mantle Rocks Around the Lunar Imbrium Basin

“…When present in high abundance, Fe‐bearing plagioclase can be identified by its diagnostic 1.25 μm band (Cheek et al, 2013; Donaldson Hanna et al, 2014). Olivine is identified by three overlapping bands centered near 1.1 μm (Arnold et al, 2016; Isaacson et al, 2014). As all three minerals have overlapping bands in the 1–1.3 μm region (Arnold et al, 2016), accurately ascertaining the relative abundance of plagioclase to the mafic minerals is difficult with VIS‐NIR data alone (Cheek & Pieters, 2014).…”