Vesuvius fumaroles (Vesuvian fumaroles), Mt Vesuvius, Somma-Vesuvius Complex, Naples, Campania, Italyi

Regional Level Types
Vesuvius fumaroles (Vesuvian fumaroles)	Group of Fumaroles
Mt Vesuvius	Volcano (Active)
Somma-Vesuvius Complex	Complex
Naples	Metropolitan City
Campania	Region
Italy	Country

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Page dedicated to the "exhalative" minerals of Vesuvius from the medieval eruptions to the present. It includes the fumarolic minerals, i.e., those minerals precipitated directly from the gas phase as volcanic sublimates or formed as a result of gas-rock interaction, as well as the incrustations formed during cooling (degassing) of lava and scoriae.

After the sub-Plinian eruption of 1631, Vesuvius' activity was characterised by periods of open-conduit activity with the alternating strombolian activity with violent eruptions. The last eruption occurred in March 1944.
During the recession periods of volcanic activity, the Vesuvian fumaroles showed a development from the high-temperature alkaline halide/sulphate, calcic sulphate or sulphidic parageneses, synchronous with or immediately following the eruptions, through medium-temperature ammonium minerals, metal chlorides, or fluoride associations to the late low-temperature paragenesis dominated by sulphur, gypsum, alunogen, and other hydrous sulphates.

Lacroix classified the Vesuvian fumaroles in four different types (Lacroix, 1908; Pelloux, 1927):
1) High-temperature fumaroles (T >300°C) with halite, sylvite, thenardite, Na-K carbonates, aphthitalite, sulphides, copper oxide and chlorides (alteration);
2) Acid fumaroles (T=300–100°C) with Mg-Fe-Al chlorides, sulphur, and realgar;
3) Salammoniac fumaroles (T around 300°C) containing salammoniac with ammonium sulphate and fluoride;
4) Sulphurous fumaroles (T around 100°C) with sulphur, gypsum, sassolite, K-Al-Fe sulphates, opal.

The relatively low-level volcanic-hydrothermal activity, which presently affects Vesuvius, is mainly characterised by: fumarolic emissions that are accompanied by diffuse soil CO₂ degassing in the crater area; CO₂-rich groundwaters along the southern flank of Vesuvius and in the adjacent plain and seismic activity with epicentres clustered inside the crater (Chiodini et al., 2001; Caliro et al., 2011). Fumarolic fluids discharging by the crater rim fumaroles are of relatively low temperatures (<75°C) and are mainly composed of atmospheric components. Fumaroles from the crater bottom have H₂O and CO₂ as the major components, followed by H₂, H₂S, N₂, CH₄, CO, and He (in order of decreasing content), and discharge temperature of about 95-100°C. CH₄ and NH3 contents suggest that the origin of these fluids could be from a high-temperature hydrothermal system located below the Vesuvius crater (Chiodini et al., 2001).

List of mineral recorded in the Vesuvius fumaroles and as incrustations on the surface or in fractures of lavas and scoriae.
- so-called 1631 lavas (actually medieval lavas of the AD 968 and 1137 eruptions, attributed in the past to a presumed effusive event linked to the 1631 eruption): atacamite, azurite, chrysocolla, gypsum, hausmannite, hematite, malachite, and "vesbine" (a mixture of mottramite and chrysocolla ± vanadinite and starovaite (rare); rarely volborthite) as encrustations in lava fractures. Anglesite, tenorite, and wulfenite has been recently identified in the mottramite paragenesis; cuprite and fluorite in the volborthite paragenesis (Balassone et al., 2019);
- 1872 eruption: atacamite, azurite, connellite, chlorocalcite, ghiaraite, halite, hematite, sylvite
- 1906 eruption: atacamite, lafossaite, realgar, dimorphite, anhydrite, and an unknown arsenic thallium chloride, probably related to lucabindiite.
- 1826 eruption:
- 1929 eruption:
- 1944 eruption: it began on March 18th and ended on the 29th of the same month. The eruption took place during wartime so that nobody was interested to sample fumarolic minerals before and just after the eruption. The whole fumarolic area was studied by Parascandola (1946, 1947, 1948, 1949, 1951, 1959, and 1960) between 1946 and 1960, when temperatures reached a maximum of about 800°C in 1950, up to the 1960s, when temperatures settled around 460°C (Parascandola, 1959 and 1960). Parascandola indicated the presence of about ten mineral species found on the fumaroles. Recent studies on the fossil fumaroles at the eastern rim and at the bottom of the crater allowed to identified other minerals, including the two new species parascandolaite and sbachiite. The list of fumarole mineral species (updated 2019) includes alum-(K), ammineite, anglesite, antlerite, artroeite, baryte, calcioaravaipaite, calcite, caledonite, cerussite, challacolloite, chrysocolla, cotunnite, creedite, cumengeite, erythrosiderite, fluorite, fluornatrocoulsellite, gearksutite, gypsum, halite, halotrichite, hematite, hydrozincite, linarite, matlockite, metavoltine, mimetite, molysite, opal, parascandolaite, paratacamite, phoenicochroite, pickeringite, salammoniac, sassolite, sbacchiite, sulphur, sylvite, tenorite, usovite, and, on the scoriae, siderazot (Parascandola, 1951, 1959, and 1960; Ragone & Ottone, 1997; Russo & Punzo, 2004; Campostrini & Gramaccioli, 2005; Cruciani et al., 2005; Russo & Campostrini, 2011; Demartin et al., 2014; Russo et al., 2014; Campostrini et al, 2019).

References

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