Ferro-fluoro-edenite, a new amphibole endmember from Vulcano Island (Sicily, Italy)

ABSTRACT Ferro-fluoro-edenite, ideally NaCa2Fe2+5(Si7Al)O22F2, was found as prismatic crystals up to 1.00 mm inside cavities in ejecta of the 1873 eruption at La Fossa crater, Vulcano Island, Aeolian Archipelago, Sicily, Italy. It is associated with quartz, magnetite, and vonsenite. Crystals are dark brown to black, transparent or semitransparent with vitreous luster, and non fluorescent. The Mohs hardness is 5–6. Cleavage is fair on {110} and fracture is uneven. Density (calc.) is 3.358 g cm–3 using the empirical formula and single-crystal cell data. The mineral is biaxial negative, α = 1.629(2), β = 1.659(2), γ = 1.667(2), 2V (calc.) = –53.8°, Y = b. Dispersion is weak to very weak, r < v, pleochroism not visible. Ferro-fluoro-edenite is monoclinic, space group C2/m, a = 9.9132(10), b = 18.1736(19), c = 5.2943(6) Å, β = 104.85(1)°, V = 922.0(2) Å3, Z = 2. The strongest X-ray diffraction peaks in the powder pattern are [d(I, hkl)]: 8.54(100, 1 1 0), 4.506(16, 0 4 0), 3.154(52, 3 1 0), 2.833(43, 3 3 0), 2.057(14, 2 0 2), 1.910(12, 5 1 0), 1.662(15, 4 6 1). The FTIR spectrum shows a broad band at about 950 cm–1 and no bands in the OH stretching region. The structure refinement led to a final R = 0.0210 for 1444 observed reflections with I > 2σ(I) and allowed cation site assignment and ordering. Microprobe analysis gave the following empirical formula calculated on the basis of 24 (O + F + Cl) apfu: (Na0.69K0.23□0.08)(Ca1.69Mg0.16Mn0.10Na0.05)Σ2(Fe2+2.86Mg2.04Ti0.10)Σ5(Si6.93Al1.05Ti0.02)Σ8O22(F1.89Cl0.09OH0.02)Σ2.

Bacterial Communities from Extreme Environments: Vulcano Island

Although volcanoes represent extreme environments for life, they harbour bacterial communities. Vulcano Island (Aeolian Islands, Sicily) presents an intense fumarolic activity and widespread soil degassing, fed by variable amounts of magmatic gases (dominant at La Fossa Crater) and hydrothermal fluids (dominant at Levante Bay). The aim of this study is to analyse the microbial communities from the different environments of Vulcano Island and to evaluate their possible correlation with the composition of the gas emissions. Microbial analyses were carried out on soils and pioneer plants from both La Fossa Crater and Levante Bay. Total DNA has been extracted from all the samples and sequenced through Illumina MiSeq platform. The analysis of microbiome composition and the gases sampled in the same sites could suggest a possible correlation between the two parameters. We can suggest that the ability of different bacterial genera/species to survive in the same area might be due to the selection of particular genetic traits allowing the survival of these microorganisms. On the other side, the finding that microbial communities inhabiting different sites exhibiting different emission profiles are similar might be explained on the basis of a possible sharing of metabolic abilities related to the gas composition.

Acmonidesite, a new ammonium sulfate chloride from La Fossa crater, Vulcano, Aeolian Islands, Italy

The new mineral acmonidesite, (NH4,K,Pb2+,Na)9Fe42+(SO4)5Cl8, was found in an active fumarole (fumarole FA, temperature ~250°C) at La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy. It occurs on a pyroclastic breccia as brown prismatic crystals up to 0.10 mm long, in association with salammoniac, alunite and adranosite. The mineral is orthorhombic, space group C2221 (no. 20) with a = 9.841(1), b = 19.448(3) c = 17.847(3) Å, V = 3415.7(9) Å3 and Z = 4. The six strongest reflections in the powder X-ray diffraction pattern are: [dobs in Å(I)(hkl)] 8.766(100)(110), 1.805(88)(390), 5.178(45)(131), 4.250(42)(221), 2.926(42)(330) and 2.684(32)(261). The empirical formula (based on 28 anions per formula unit [pfu]) is (NH4)5.77K1.42Pb0.62Na1.24Fe3.96Mn0.08S5.04O20.16Cl7.97Br0.08. The idealised formula is (NH4,K,Pb2+,Na)9Fe42+(SO4)5Cl8. The calculated density is 2.551 g cm–3. Using single-crystal diffraction data, the structure was refined to a final R(F) = 0.0363 for 4614 independent observed reflections [I > 2σ(I)]. The structure contains two independent, distorted octahedral iron sites, Fe1 and Fe2, with the iron atoms in the 2+ oxidation state, as confirmed by the interatomic distances and bond-valence calculations (2.06 and 1.94 vu, respectively). Fe1 is surrounded by two chlorine atoms and four oxygens of the sulfate ions, with the following average distances (Å): Fe1–O 2.125 and Fe1–Cl 2.472; and Fe2 is surrounded by three chlorine atoms and three oxygens of the sulfate ions, with the following average distances (Å): Fe2–O 2.110 and Fe2–Cl 2.531. Three independent sulfate anions are also present and are connected with the iron polyhedra to form a three-dimensional structure containing voids occupied by four independent ammonium ions (two of them partially replaced by K+), one Na+/Pb2+ site and one Cl– ion.

Fluorite-related one-dimensional units in natural bismuth oxysulfates: the crystal structures of Bi14O16(SO4)5and Bi30O33(SO4)9(AsO4)2

The crystal structures of two new natural Bi oxysulfates with the formula Bi14O16(SO4)5[labellednew phase I; monoclinic, space groupC2,a= 21.658 (4),b= 5.6648 (9),c= 15.092 (3) Å, β = 119.433 (11)° andZ= 2] and Bi30O33(SO4)9(AsO4)2[labellednew phase II; triclinic, space groupP1,a= 5.670 (3),b= 13.9408 (9),c= 22.7908 (18) Å, α = 80.903 (5), β = 82.854 (14), γ = 78.27 (2)° andZ= 1] from the high-temperature fumarole deposit of the La Fossa crater at Vulcano (Aeolian Islands, Italy) are reported. The structures are built up by a combination of fluorite-related Bi—O units and isolated (SO4)2−tetrahedra (new phase I) or both (SO4)2−and (AsO4)3−tetrahedra (new phase II). Owing to the effect of stereoactive lone pairs of Bi3+, Bi—O units in both the structures can be suitably described in terms of oxo-centered OBi4tetrahedra. The structure of Bi14O16(SO4)5is based upon one-dimensional [O16Bi14]10+ribbons formed by six chains of edge-sharing OBi4tetrahedra extending along [010]. In the structure of Bi30O33(SO4)9(AsO4)2the same ribbon type coexists with another one-dimensional ribbon formed by seven chains of edge-sharing OBi4tetrahedra and with the composition [O17Bi16]14+. Ribbons of the same type are joined by (SO4)2−and (AsO4)3−tetrahedra along [010] – if a reduced triclinic unit-cell setting is considered – so forming two different (001) slabs which alternate to each other along [001] and are joined by additional (SO4)2−tetrahedra.New phase Irepresents the natural analogues of synthetic Bi14O16(SO4)5, but with an ordered structure model.

Campostriniite, (Bi3+,Na)3(NH4,K)2Na2(SO4)6·H2O, a new sulfate isostructural with görgeyite, from La Fossa Crater, Vulcano, Aeolian Islands, Italy

The new mineral campostriniite, (Bi3+,Na)3(NH4,K)2Na2(SO4)6·H2O, was found in an active fumarole (fumarole FA, temperature ∼350°C) at La Fossa Crater, Vulcano, Aeolian Islands, Sicily, Italy. It occurs on a pyroclastic breccia as white prismatic crystals up to 0.2 mm long, in association with adranosite, demicheleite-(Br), demicheleite-(I), argesite and sassolite. The mineral is monoclinic, space group: C2/c (no. 15) with a = 17.748(3), b = 6.982(1) c = 18.221(3) Å, β = 113.97(1)°, V = 2063(1) Å3 and Z = 4. The six strongest reflections in the powder X-ray diffraction pattern are: [dobs in Å (I)(hkl)] 6.396(100)(110), 7.507(75)(202), 2.766(60)(316), 3.380(57)(312), 5.677(55)(111), 3.166(50)(4 0 2). The empirical formula (based on 25 anions p.f.u.) is Bi2.41N1.52Na2.41K0.48 S6.07H8.08O25. The calculated density is 3.87 g cm–3. Using single-crystal diffraction data, the structure was refined to a final R(F) = 0.051 for 3025 independent observed reflections [I > 2σ(I)]. Campostriniite is isostructural with görgeyite and belongs to the 7.CD group of the Strunz classification system. The structure contains two independent nine-fold coordinated sites, one of them located on a two-fold axis (M1) and the other one in general position (M2) essentially occupied by Bi3+ atoms and minor amounts of Na+ ions, an eight-fold coordinated site fully occupied by Na +ions and another eight-fold coordinated site occupied by NH+4 and K+ ions; three independent sulfate anions in a general position and a water molecule coordinated to M1 and located on a two-fold axis are also present.

The crystal structure of balićžunićite, Bi2O(SO4)2, a new natural bismuth oxide sulfate

The crystal structure of balićžunićite, Bi2O(SO4)2, a new mineral species from the La Fossa crater of Vulcano (Aeolian Islands, Italy), was solved from single-crystal X-ray diffraction data and refined to R = 0.0507. The structure is triclinic, space group P1, with a = 6.7386(3), b = 11.1844(5), c = 14.1754(7) Å, α = 80.082(2), β = 88.462(2)°, γ = 89.517(2)°, V = 1052.01(8) Å3 and Z = 6. The crystal structure consists of six independent Bi sites, six S sites and 27 O sites of which three are oxo oxygen atoms not bonded to sulfur. Bismuth and S atoms are arranged close to a eutectic pattern parallel to the (100) plane. The planes are stacked atom on atom such that Bi always overlays S and vice versa. This structural feature is shared with the known structure of the high-temperature polymorph of the same compound, stable at T >535°C. However, the sequences of Bi and S atoms in the two structures are different and so are the arrangements of oxygen atoms. Characteristic building blocks in the structure of balićžunićite are clusters of five Bi atoms which form nearly planar trapezoidal Bi5 groups with oxo oxygens located in the centres of the three Bi3 triangles, which form the trapezoids. The trapezoidal Bi5O39+ ions are joined along [100] with SO42– groups by means of strong bismuth-sulfate oxygen bonds, forming infinite [100] rods with composition Bi5O3(SO4)5–. One sixth of the Bi atoms do not participate in trapezoids, but form, with additional SO42– groups, rows of composition BiSO4+, also parallel to [100]. [Bi5O3(SO4)5–] rods form infinite layers parallel to (010) with [BiSO4+] rows located on the irregular surface of contact between adjacent layers. Bi atoms occur in four different coordination types, all showing the stereochemical influence of the Bi3+ lone electron pair. In this respect the crystal structure of balićžunićite shows greater variability than its high-temperature polymorph which has only two types of the Bi coordination spheres present in balićžunićite.

Leguernite, Bi12.67O14(SO4)5, a new Bi oxysulfate from the fumarole deposit of La Fossa crater, Vulcano, Aeolian Islands, Italy

Leguernite, ideally Bi12.67O14(SO4)5, is a new mineral found in high-temperature fumarolic assemblages at La Fossa crater, Vulcano, Aeolian Islands, Italy. It occurs as aggregates of needleshaped crystals associated strictly with anglesite, balićžunićite and an unknown Bi sulfate. Leguernite is colourless to white, transparent, non-fluorescent, has a sub-adamantine lustre and a white streak. Electron microprobe data led to the chemical formula (on the basis of 34 anions p.f.u.) (Bi12.40Pb0.15)Σ=12.55S5.08O34. The calculated density is 7.375 g cm–3. A Raman spectrum collected on a single crystal of leguernite confirmed the anhydrous nature of the mineral.Leguernite is monoclinic, space group P2, with a = 11.2486(11), b = 5.6568(6), c = 11.9139(10) Å , β = 99.177(7)º, V = 748.39(12) Å3 and Z = 1. The crystal structure is built up of Bi–O blocks of a fluorite-like structure with Bi12O14 composition separated by a single sulfate ion along [100] and by Bi(SO4)45– groups along [101]. It can also be described as composed of (001) layers with composition [Bi12O14(SO4)6+]n alternating with layers of composition [Bi(SO4)4]n5– along [001]. Leguernite shows significant similarities with the synthetic Bi14O16(SO4)5 compound.The eight strongest reflections in the powder X-ray diffraction data [d in Å (I) (hkl)] are: 3.220 (100) (013), 3.100 (95) (11), 2.83 (30) (020), 2.931 (25) (302), 2.502 (25) (04), 2.035 (20) (322), 1.875 (20) (24) and 5.040 (15) (110).The name is in honour of Franc¸ois “Fanfan” Le Guern (1942–2011), who was a very active volcanologist and specialist in volcanic gases and sublimates. Both the mineral and the mineral name have been approved by the IMA-CNMNC (2013–051).

Balićžunićite, Bi2O(SO4)2, a new fumarole mineral from La Fossa crater, Vulcano, Aeolian Islands, Italy

Balićžunićite, ideally Bi2O(SO4)2, is a new mineral found as a high-temperature fumarole sublimate (T = 600°C) at La Fossa crater, Vulcano, Aeolian Islands, Italy. It occurs as aggregates of mm-sized prismatic and elongated crystals (∼50 μm across and up to 200 μm long) associated with anglesite, leguernite, one other potentially new Bi-oxysulfate mineral, lillianite, galenobismutite, bismoclite, Cd-rich sphalerite, wurtzite, pyrite and pyrrhotite. Balićžunićite is colourless to white or pale brown, transparent and non-fluorescent. It has a vitreous lustre and a white streak. Electron microprobe analysis gives the following average chemical composition (wt.%): Bi2O3 68.68 and SO3 23.73, total 92.41. The empirical chemical formula, calculated on the basis of 9 anions p.f.u., is Bi1.99S2O9. The calculated density is 5.911 g/cm3.Balićžunićite is triclinic, space group P, with a 6.7386(3), b 11.1844(5), c 14.1754(7) Å, α 80.082(2)°, β 88.462(2)°, γ 89.517(2)°, V = 1052.01(8) Å3 and Z = 6. The six strongest reflections in the X-ray powder-diffraction data [d in Å(I) (hkl)] are: 3.146 (100) (033), 3.486 (21) (004), 3.409 (12) (01), 3.366 (7) (200), 5.562 (4) (11), 5.433 (4) (111). Balićžunićite is the natural analogue of the stable low-temperature a form of synthetic Bi2O(SO4)2. The name is in honour of Tonci Balić-Žunić(born 1952), Professor of Mineralogy at the Natural History Museum of the University of Cophenagen. Both the mineral and the mineral name have been approved by the IMA-CNMNC Commission (IMA2012-098).

Therasiaite, (NH4)3KNa2Fe2+Fe3+(SO4)3Cl5, a new sulfate chloride from La Fossa Crater, Vulcano, Aeolian islands, Italy

The new mineral therasiaite, ideally (NH4)3KNa2Fe2+Fe3+(SO4)3Cl5, was found in a mediumtemperature (∼250°C) intracrater active fumarole at La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy. It occurs on a pyroclastic breccia as brown to dark brown equant to short prismatic crystals up to 0.1 mm in length, in association with salammoniac, kremersite and adranosite. The mineral is monoclinic, space group: Cc (no. 9) with a = 18.284(4), b = 12.073(2), c = 9.535(2) Å, β = 108.10(3)°, V = 2000.6(7) Å3 and Z = 4. The six strongest reflections in the X-ray powder diffraction pattern are: [dobs in Å(I)(hkl)] 2.812(100)(23), 2.664(77)(13), 3.297(28)(33), 3.208(14)(2), 3.008(12)(040), 2.942(11)(331). The empirical formula (based on 17 anions per formula unit (p.f.u.)) is (NH4)2.68K1.32Na2.04Fe1.76Al0.12Mn0.12S2.98O11.95Cl5.05. The measured density is 2.41(1) g cm−3, dcalc = 2.395 g cm−3. The mineral is biaxial (−) with α= 1.585(3) β = 1.615(3) and γ = 1.630(3) (white light). Using single-crystal diffraction data, the structure was refined to a final R(F) = 0.0240 for 5574 independent observed reflections [I > 2σ(I)]. The structure of therasiaite displays a novel topology and contains two independent, distorted octahedral Fe sites, with the Fe atoms in oxidation state 3+ and 2+, respectively, each surrounded by three Cl atoms and three oxygens of the sulfate ions. The Fe octahedra and the three independent sulfate anions are connected to form chains running along [001]. Voids between the chains are occupied by three independent ammonium ions (partially replaced by K+), one K+ and two Na+ ions. The formula resulting from the structure refinement is [(NH4)2.25K0.75]KNa2Fe2(SO4)3Cl5.