Storia termica di una fumarola del Vesuvio (Campania, Italy) attraverso lo studio di minerali presenti su di un microcampione

Abstract

Alava scoria sample rich in crystals, from a fumarole of the 1906 eruption, has been examined in the present work. The analyses of the sample were performed by an EDS-equipped scanning electron microscope which made possible to identify galena, sphalerite, challacolloite and gypsum; these minerals can be considered as temperature-markers. At first the fumarole was in high temperature conditions (higher than 650°C and however not lower than 400-300°C) with deposition of galena and sphalerite. When temperature decreased a film of challacolloite (KPb2Cl5) was formed and coated the existing minerals. Finally, after a sudden drop in temperature gypsum was formed. These findings are in agreement with the formation of galena and sphalerite into silica tubes placed in fumaroles of others volcanoes, according the methodology proposed by [Le Guern e Bernard, 1982].