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Iron-rich clay minerals on Mars - Potential sources or sinks for hydrogen and indicators of hydrogen loss over timeAlthough direct evidence is lacking, indirect evidence suggests that iron-rich clay minerals or poorly-ordered chemical equivalents are widespread on the Martian surface. Such clays can act as sources or sinks for hydrogen ('hydrogen sponges'). Ferrous clays can lose hydrogen and ferric clays gain it by the coupled substitution Fe(3+)O(Fe(2+)OH)-1, equivalent to minus atomic H. This 'oxy-clay' substitution involves only proton and electron migration through the crystal structure, and therefore occurs nondestructively and reversibly, at relatively low temperatures. The reversible, low-temperature nature of this reaction contrasts with the irreversible nature of destructive dehydroxylation (H2O loss) suffered by clays heated to high temperatures. In theory, metastable ferric oxy-clays formed by dehydrogenation of ferrous clays over geologic time could, if exposed to water vapor, extract the hydrogen from it, releasing oxygen.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Burt, D. M.
(Arizona State University Tempe, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1989
Subject Category
Lunar And Planetary Exploration
Meeting Information
Meeting: Lunar and Planetary Science Conference
Location: Houston, TX
Country: United States
Start Date: March 14, 1988
End Date: March 18, 1988
Accession Number
Funding Number(s)
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