Variations in Visible/Near-Infrared Hematite Spectra Related to Grain Size and CrystallinityDrill fines created by the Curiosity rover at Gale Crater, Mars have exhibited variable visible/near-infrared spectral features attributable to the presence of ferrous and ferric minerals. Drilled locations within the Murray formation and on the Vera Rubin Ridge (VRR) were shown by the CheMin instrument to contain significant amounts of hematite. However, typical hematite spectral features (e.g., absorptions near 530 nm and 860 nm) have varied inconsistently with hematite abundances. This suggests that other factors such as hematite grain size or crystallinity, the presence of amorphous materials, and/or photometric effects play a role in the observed spectra. Using laboratory spectra of hematite acquired at difference grain sizes, we document the variability in key spectral features. We also compare spectral parameters computed from Mastcam spectra on Mars of three hematite-bearing ChemCam calibration target (CCCT) samples with known hematite and amorphous material abundances.
Document ID
20190001841
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Johnson, J. R. (Johns Hopkins Univ. Laurel, MD, United States)
Cloutis, E. (Winnipeg Univ. Manitoba, Canada)
Fraeman, A. A. (California Institute of Technology Pasadena, CA, United States)
Bell, J. F. III (Arizona Univ. Phoenix, AZ, United States)
Wellington, D. (Arizona Univ. Phoenix, AZ, United States)
Horgan, B. (Purdue Univ. Indianapolis, IN, United States)
Rampe, E. (NASA Johnson Space Center Houston, TX, United States)
Vaniman, D. (Planetary Science Inst. Pasadena, CA, United States)
Pinet, P. (Research Inst. in Astrophysics and Planetology (IRAP) Toulouse, France)