Mixed-valence iron minerals on Venus: Fe(2)-Fe(3) oxides and oxy-silicates formed by surface-atmosphere interactions

摘要

Inferences from these investigations are that Fe(3)-bearing minerals such as hematite magnesioferrite, acmite, and epidote are thermodynamically unstable, and that magnetite is the predominant mixed-valence iron oxide mineral on venus. Recently, the Fe(2)-Fe(3) silicate mineral laihunite was proposed to be a reaction product of olivine with the venusian atmosphere. This possibility is discussed further here. We suggest that other mixed-valence Fe(2)-Fe(3)-Oz-OH(-) silicates could also result from surface-atmosphere interactions on Venus. Topics discussed include the following: (1) conversion of hematite to magnetite; (2) stability of laihunite; (3) the possible existence of oxy-amphiboles and oxy-micas on Venus; and (4) other mixed-valence Fe(2)-Fe(3) silicates likely to exist on Venus.