Annotated record of the detailed examination of Mn deposits from the coastal vicinity of the Vulcano Island in the Eolian Islands, Italy

The volcanic deposits which surround Vulcano Island may be classified in four phases : a detritic phase, fed from the Island itself and from Sicily; a siliceous and carbonateous organic phase; a neogenesis mineral phase; a precipitation phase. The formation of clay and the mineralization of iron and manganese are the subject of particular study. A number of indications suggest the littoral neogenesis of kaolinite around hydrothermal issues, and the formation of smectite at greater depths. The distribution of iron mineralization in the Baie du Levant follows the physicochemical variations of the environment. Melnikovite, pyrite, marcassite and pyrrhotin are dispersed in aureoles around swallow emission points (fumaroles). Close to the hydrothermal spring, iron precipitates are found in the form of amorphous hydroxydes, while geothite and hematite characterize the deeper area as a whole. Manganese mineralizations are exclusively represented by hydroxides and oxides, locally (about - 250 m) organized as incrustations on. lapilli glasses (micronodules). These would appear to be related to the hydrothermal spring.