In Situ Detection of Opal‐A in Jezero Crater, Mars
Year: 2026
Type: article
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.
DOI: 10.1029/2025je009375
Authors: Sergei V. Bykov, Kenneth H. Williford, Anushree Srivastava, Andrew Steele, Linda C. Kah, Travis A. Olds, Sunanda Sharma, Richard V. Morris, Kimberly Poppy Sinclair, Ryan S. Jakubek, Nikole C. Haney, Francis M. McCubbin, Mariek E. Schmidt, Ashley E. Murphy, Sandra Siljeström, Eva L. Scheller, William Abbey, Sanford A. Asher, Kevin P. Hand, Kyle Uckert, Jeffrey T. Osterhout, Carina Lee, Rohit Bhartia, Michelle E. Minitti, Joanna V. Clark, Patrick Casbeer, Shiv K. Sharma
Institutions: University of Pittsburgh, Blue Marble Space Institute of Science, Carnegie Institution for Science, University of Tennessee at Knoxville, Carnegie Museum of Natural History, University of Hawaiʻi at Mānoa, Johnson Space Center, University of Washington, Brock University, Planetary Science Institute, RISE Research Institutes of Sweden, Stanford University, Jet Propulsion Laboratory, California Institute of Technology, Photon Systems (United States)
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,070
OpenAlex ID: W7160077936