Sulfur dioxide is the most abundant sulfur-bearing volcanic gas species on Earth, with approximately 10 Mt SO2 emitted from volcanoes globally each year. From its largely magmatic source at depths of 3 to 6 km below the surface, SO2 expands through the subvolcanic environment where it interacts with volcanic rocks at high temperature. The reaction between SO2 and silicate rocks forms oxidized sulfate and reduced sulfide. This reaction is a key process in the formation of porphyry copper and gold deposits. In volcanic eruption plumes SO2 reacts with volcanic ash and it is scavenged onto ash particles. Similarly, SO2 is a major volcanic gas in volcanic eruptions on Venus and Jupiter’s moon Io and in Mars’s past eruptions. Thus, reactions between SO2 and rocks likely altered the composition and mineralogy of the crusts on these planetary bodies.
To identify how SO2 + glass reactions occur at high temperature and to investigate what might promote and limit these reactions, I present results from an experimental study. Pure SO2 was reacted with silicate glasses in the system anorthite-diopside-albite and natural basaltic glasses. Results suggest that the structural property of the silicate glass substrate controls the diffusive transport of Ca, Na and Mg to the surface which in turn controls the overall reaction rate and the formation of sulfates, oxides and silicates. My findings can be applied to predicting reactions on planetary surfaces and at shallow levels within their crusts.