In Situ Detection of Opal‐A in Jezero Crater, Mars

Abstract We report the in situ detection of amorphous hydrated silica in the Bills Bay abrasion patch, located in the eastern portion of the Margin Unit between the rim of Jezero crater and the western delta. Here, hydrated silica co‐occurs with olivine, Fe‐Mg carbonates, secondary Fe‐Mg silicates, and hydrated Mg‐sulfate as determined by UV Raman (SHERLOC) and X‐ray fluorescence (PIXL) spectrometers onboard the Perseverance rover. Almost pure hydrated silica fills the intergranular space between olivine and carbonate‐bearing domains. We performed Raman analysis of terrestrial opals with various crystallinities including opal‐AN, AG, CT, and C. We found that the Si − O symmetric stretching Raman band at ∼800 cm −1 is sensitive to opal crystallinity, yet insensitive to ambient temperature (at ∼77–293 K) and silica hydration. We identified the crystal structure of the Bills Bay Hydrated Silica (BBHS) as opal‐A. Furthermore, we developed a Raman methodology to quantify opal‐A hydration. We found that the total amount of hydration in the BBHS phases was 1.7 ± 0.2 wt. %. Most of this hydration, 1.5 ± 0.2 wt. %, reflects the presence of silanol groups. Our analysis revealed that the Raman spectrum of BBHS closely resembles that of opal‐A that has lost most of its molecular water. The composition and textures of the Bills Bay abrasion indicate that BBHS is derived from olivine carbonation. Opal‐A is the only silica polymorph identified in the SHERLOC data. We hypothesized that silica precipitation occurred, either during the late stages of a major carbonation event or during a brief, subsequent aqueous alteration event unrelated to carbonation.

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Publication Details

Journal
Journal of Geophysical Research Planets
Published
2026-04-30
DOI
https://doi.org/10.1029/2025je009375
Primary Topic
Mineralogy and Gemology Studies
Type
article
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article

In Situ Detection of Opal‐A in Jezero Crater, Mars

Eva L. Scheller, M. E. Minitti, J. V. Clark, Kyle Uckert et al.
Journal of Geophysical Research Planets
Mineralogy and Gemology Studies
article

In Situ Detection of Opal‐A in Jezero Crater, Mars

Eva L. Scheller, M. E. Minitti, J. V. Clark, Kyle Uckert, Shiv K. Sharma, Nikole C. Haney, Sanford A. Asher, R V Morris, Kenneth H. Williford, M. E. Schmidt, Travis A. Olds, Jeffrey T. Osterhout, Sergei V. Bykov, Kimberly Poppy Sinclair, Carina Lee, Patrick Casbeer, Sunanda Sharma, Ryan S. Jakubek, Andrew Steele, Sandra Siljeström, Rohit Bhartia, Anushree Srivastava, William Abbey, Linda C. Kah, Kevin P. Hand, Ashley E. Murphy, Francis M. McCubbin
article en

Abstract

Abstract We report the in situ detection of amorphous hydrated silica in the Bills Bay abrasion patch, located in the eastern portion of the Margin Unit between the rim of Jezero crater and the western delta. Here, hydrated silica co‐occurs with olivine, Fe‐Mg carbonates, secondary Fe‐Mg silicates, and hydrated Mg‐sulfate as determined by UV Raman (SHERLOC) and X‐ray fluorescence (PIXL) spectrometers onboard the Perseverance rover. Almost pure hydrated silica fills the intergranular space between olivine and carbonate‐bearing domains. We performed Raman analysis of terrestrial opals with various crystallinities including opal‐AN, AG, CT, and C. We found that the Si − O symmetric stretching Raman band at ∼800 cm −1 is sensitive to opal crystallinity, yet insensitive to ambient temperature (at ∼77–293 K) and silica hydration. We identified the crystal structure of the Bills Bay Hydrated Silica (BBHS) as opal‐A. Furthermore, we developed a Raman methodology to quantify opal‐A hydration. We found that the total amount of hydration in the BBHS phases was 1.7 ± 0.2 wt. %. Most of this hydration, 1.5 ± 0.2 wt. %, reflects the presence of silanol groups. Our analysis revealed that the Raman spectrum of BBHS closely resembles that of opal‐A that has lost most of its molecular water. The composition and textures of the Bills Bay abrasion indicate that BBHS is derived from olivine carbonation. Opal‐A is the only silica polymorph identified in the SHERLOC data. We hypothesized that silica precipitation occurred, either during the late stages of a major carbonation event or during a brief, subsequent aqueous alteration event unrelated to carbonation.

Journal of Geophysical Research PlanetsVol. 131(5)
University of Hawaiʻi at Mānoa (US), California Institute of Technology (US), Planetary Science Institute (US), Carnegie Museum of Natural History (US), Jet Propulsion Laboratory (US), University of Pittsburgh (US), Brock University (CA), Carnegie Institution for Science (US), University of Washington (US), Carnegie Museum of Art (US), RISE Research Institutes of Sweden (SE), Photon Systems (United States) (US), Blue Marble Space (US), Johnson Space Center (US), Blue Marble Space Institute of Science (US), Earth and Space Research (US), University of Tennessee at Knoxville (US)
Life below water
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Mineralogy and Gemology Studies
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