Electrochemical Study of Iron Oxide Deposits in Weathered

The chemical and crystallographic composition of iron oxide deposits resulting from the alteration of glasses was studied using the voltammetry of microparticles approach upon sample attachment to paraffin-impregnated graphite electrodes immersed into aqueous HCl. Square wave voltammetry allows to characterize amorphous, highly hydrated iron oxides, crystalline hematite and goethite and their hydrated forms are recorded in weathered glasses. Samples from five archaeological sites in the Valencian Community (Spain) were studied using this approach. It is suggested that formation of different iron oxide deposits results from the existence of a significant gradient of water concentration within the gel layer formed throughout the weathering process