Sublimate deposition from hydrothermal fluids at the Fossa Crater, Vulcano, Italy
Sublimate deposition from hydrothermal fluids at the Fossa Crater, Vulcano, Italy (in EMPG-VI; Experimental mineralogy, petrology and geochemistry, E. A. J. Burke (editor), C. Chopin (editor), W. V. Maresch (editor), L. Ungaretti (editor) and C. Willaime (editor))
European Journal of Mineralogy (April 1997) 9 (2): 423-432
Sublimates were sampled at the Fossa crater of Vulcano Island, Sicily, by means of silica tubes inserted into fumarolic vents around which Pb and Bi sulphides and sulphosalts occurred. The main phase found within the silica tubes were native sulphur, ammonium tetrafluroroborate, lead and bismuth chlorides, oxychlorides, sulphochlorides, sulphides and sulphosalts. The Pb and Bi mineral assemblage is interpreted as the result of transport of Pb and Bi as volatile chlorides. Microtextural and microanalytical studies on chlorosulphides and sulphosalts suggest that the latter were deposited from metastable chlorosulphides through reactions involving H (sub 2) S. The lack of sulphates in the silica tubes is due to the reducing conditions of volcanic fluids.