Reflectance Spectroscopy of Ferric Sulfate-Bearing Montmorillonites as Mars Soil Analog Materials

Low Abundance Materials at the Mars Pathfinder Landing Site: An Investigation Using Spectral Mixture Analysis and Related Techniques

“…These soil deposits generally exhibit a ∼5% deep 900-nm absorption, with an even deeper band occurring in the smaller occurrences noted in the RMS error images. The smaller clusters with the deeper 900-nm band might be smaller occurrences of a more fractionally abundant or coarser-grained cementing agent like a ferric oxide or oxyhydroxide (e.g., Clark and Van Hart 1981, Bishop et al 1995, which in the larger occurrences of Intermediate Soil is spectrally masked by other lower albedo sedimentary grains. Alternately, this narrow short wavelength feature may indicate the presence of low-Ca pyroxene (e.g., Sunshine and Pieters 1993, Bishop et al 1998, presumably from intermixed subresolution rock or soil fragments.…”

Use and Limitations of Second-Derivative Diffuse Reflectance Spectroscopy in the Visible to Near-Infrared Range to Identify and Quantify Fe Oxide Minerals in Soils

“…With the exception of hematite and magnetite, however, the unequivocal discrimination of Fe oxide minerals cannot be performed by using the positions of the crystal field bands only. A better result may be achieved by including the vibrational bands into the discriminant analysis (Coyne et al 1990;Bishop et al 1995;Bishop and Murad 1996). ACKNOWLEDGMENTS ACS acknowledges the research grant by the Deutsche Forschungsgemeinschaft, and thanks D. G. Schulze (Purdue University) who gave the visiting scientist a warm welcome and provided the equipment, R. V. Morris (NASA, Houston, Texas) for his introduction into the secrets of diffuse reflectance spectroscopy and U. Schwertmann (Technische Universit~it Mtinchen, Germany) who generously provided his large collection of Fe oxides.…”

“…We restricted this study to the evaluation of crystal field bands. The OH and H20 vibrational bands in the IR constitute, however, another possibility for characterizing Fe oxides (Bishop et al 1995;Bishop and Murad 1996).…”

Morphogenesis of Antarctic Paleosols: Martian Analogue

“…Recently, the thermal emission spectrometer on the Mars Global Surveyor has been used to determine the distribution of sulfate (SO 3 ) cemented soils (Cooper and Mustard 2001).The sulfate is not located in topographic lows, arguing that the soil was cemented by an atmospherically driven process. Although Bishop et al (1995) have shown that the reflectance spectra of ferrihydrite and ferric sulfate-bearing montmorillonite resemble martian bright region spectra, the mineralogy of the martian soil is generally characterized by the lack of spectral evidence for wellcrystallized clay minerals due to abundant water. The absence of evidence for abundant clays has led to alteration models involving palagonitization (Singer 1982), or an "acid-fog" mechanism (Banin et al 1997).…”