Effect of iron metal and siderite on the durability of simulated archeological glassy material

• Laboratory experiments were performed on a glass simulating archeological artifacts.
• Experimental conditions reproduced in situ anoxic and clay-type environment.
• The effects of siderite and metal iron on glass leaching were investigated.
• Siderite led to a moderate and transient effect limited by silica sorption.
• With metal iron, glass corrosion is durably sustained by the precipitation of Fe-silicates.

Under anoxic conditions, the presence of iron is expected to enhance the alteration rate of silicate glass. In order to understand the underlying mechanisms, experiments were performed on a synthetic glass simulating archeological artifacts to study the effect of metallic iron and siderite in a clay-type groundwater. Characterization of the altered samples at different durations reveals different impacts of iron on glass alteration. In contact with siderite, the sorption of the released silicon maintains temporarily a high alteration rate which eventually drops. With metallic iron, glass is altered near the maximum dissolution rate throughout the experiment because of Fe-silicate precipitation.

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