Fluorophlogopite, a new F-dominant mineral of the mica group, was found at Monte Calvario, Biancavilla, lower southwestern flanks of Mt. Etna volcano (Catania, Sicily, Italy). The mineral occurs in autoclasts of gray-red altered benmoreitic lavas, primarily associated with fluoro-edenite, alkali-feldspars, clino- and ortho-pyroxenes, fluorapatite, hematite, and pseudobrookite. It was formed by metasomatism of the original lava rocks from very hot fluid enriched in F, Cl, and other incompatible elements. Fluorophlogopite occurs as very thin laminae with a diameter of 200 to 400 μm. Main physical properties are pale yellow in color; yellowish-white in thin section; vitreous to resinous luster; transparent; non-fluorescent; Mohs’ hardness 2–3; brittle and malleable; perfect cleavage on {001}; biaxial (–), αcalc = 1.5430(8), β = 1.5682(5), γ = 1.5688(5) (λ = 589 nm); 2Vmeas = 17(2)°; α = acute bisectrix ⊥ (001); nonpleochroic; Dcalc = 2.830 g/cm3 (using empirical formula and single-crystal unit-cell parameters), Dcalc = 2.842 g/cm3 (using empirical formula and powder cell constants). Infrared spectrum did not show a significant absorption band in the OH-stretching region (3800–3600 cm–1) confirming that the F content of the fluorophlogopite from Biancavilla is close to the stoichiometric value. Unit-cell parameters from X-ray powder-diffraction data (114.6 mm diameter Gandolfi camera, CuKα) are a = 5.305(2), b = 9.189(3), c = 10.137(4) Å, β = 100.02(3)°. These data agree with those obtained by single-crystal X-ray studies on a very thin (~15 μm) fluorophlogopite crystal, i.e., Monoclinic (1M polytype); Space Group C2/m; a = 5.3094(4), b = 9.1933(7), c = 10.1437(8) Å, β = 100.062(5)°, V = 487.51(6) Å3, Z = 2. Structure refinements using anisotropic displacement parameters converged at R = 3.50, Rw = 4.37, Rsym = 3.72%. Electron microprobe analysis performed on the same crystal used for X-ray investigation gave: SiO2 = 45.75(39), TiO2 = 1.05(5), Al2O3 = 9.60(19), MgO = 27.92(30), MnO = 0.16(3), FeOtot = 1.25(6), BaO = 0.09(5), K2O = 8.22(11), Na2O = 0.61(30), Cl = 0.02(1) wt%. Secondary Ion Mass Spectrometry (SIMS) was used to estimate light elements [Li2O = 0.30(1) and H2O = 0.16(2) wt%] and fluorine content [F = 8.69(24) wt%]. The new mineral fluorophlogopite and its name were approved by IMA-CNMMN (2006/011)

Fluoro-edenite [NaCa 2 Mg 5 (Si 7 Al)O 22 F 2 ], a new end-member of the calcic amphibole group, is present with both prismatic and fi brous morphologies in the altered volcanic products of the Monte Calvario locality, Biancavilla, on the fl anks of Mount Etna, Sicily, Italy. Whereas the crystal chemistry of the prismatic variety was described recently, the fi brous variety has not been well characterized. We report original crystal-chemical and structural data on this fi brous amphibole. Because of the diffi culty in analyzing this micrometric material, specifi c procedures of sample preparation were developed. SEM-EDS microanalyses and Mössbauer spectroscopy indicate a variable composition of the fi bers, ranging mostly from fl uoro-edenite to, subordinately, winchite, tremolite, and richterite compositions. Given the impossibility of using a single-crystal X-ray method, the powderdiffraction data were evaluated by the Rietveld method. By combining the microchemical data, Mössbauer Fe 3+ /Fe tot values, and with a refi nement of the structure, the following chemical formula was obtained from an averaged composition of all the fi brous amphibole analyzed: (Na 0.307 K 0.157) ⌺0.464 (Ca 1.505 Na 0.495) ⌺2.000 (VI Al 0.104 Fe 3+ 0.333 Fe 2+ 0.162 Mg 4.255 Ti 0.062 Mn 0.063) ⌺4.980 (Si 7.520 IV Al 0.480) ⌺8.000 O 22 (F 1.970 Cl 0.020) ⌺1.990. The cell parameters, positional parameters for all the atoms, and site scattering for O3, M1, M2, M3, M4, A, and A(m) were refi ned. In agreement with the site occupancies of cations based on both XRPD and Mössbauer data, Fe 2+ was assigned to the M2 and M3 sites, and all Fe 3+ was assigned to the M2 site. In particular, Fe 2+ content of each M2 site is far greater (0.125 apfu) than that of M3 (0.037 apfu). The analytical procedures utilized here can be adopted for all types of mineral fi bers, whether they belong to the asbestiform group of amphiboles or not. In addition to their mineralogical interest, these results are also relevant for environmental and health aspects. The interactions between mineral fi ber and the biological environment are strongly related to the crystal chemistry of the fi brous materials.

This study reports new spectroscopic and structural data of fibrous amphiboles from the volcanic area of Biancavilla (Sicily, Italy) that generated interest because of an anomalous increase of pleural mesothelioma of inhabitants. Each of the four samples is made of loose fibers, which show an edenite-winchite (fluorine) compositional trend, with significant tremolite component. Small amounts of iron (3.6-6.0 wt% FeO(tot)) were identified in all samples, and the Fe(3+)/Fe(tot) ratios were evaluated by Mossbauer spectroscopy: two samples are characterized by Fe(3+)/Fe(tot) ratios between 50 and 70%, and the other two have Fe(3+)/Fe(tot) ratios higher than 90%. The OH-stretching region was investigated by FTIR, and no absorption bands were observed. Structural investigation was carried out by X-ray powder diffraction using the Rietveld method. Cell parameters, positional parameters for all the atoms, and site scattering for M1, M2, M3, M4, A, and A(m) were refined. The most important differences with respect to prismatic fluoro-edenite are the decrease of beta, a, and c with decreasing Ca content, A-site occupancy, and tetrahedral Al content, respectively. By combining chemical, spectroscopic, and structural data, possible site occupancies were obtained. In particular, it was found that Fe(2+) is distributed between M1 and M2 sites; moreover, for the two samples enriched in Fe(2+), it is also present at M4. Fe(3+) is generally ordered at M2 site; however, for the two samples enriched in Fe(3+), minor amounts are partially disordered between M1 and M3 sites. For the Biancavilla amphibole fibers, the large compositional variation observed in every sample makes the classification very difficult, so that the regulatory agencies would not classify as "asbestos" the whole mineral series, because of the large components of edenite and winchite in addition to tremolite. Many common features were found with respect to amphibole fibers from Libby, Montana, including Fe contents and oxidation state. Preliminary results of in vitro toxicological tests on Biancavilla fibers confirmed their high reactivity, and suggest that the samples with the highest Fe(2+) contents induce a rapid start to cell mortality

No abstract

Mineralogical and geochemical studies were undertaken in the volcanic area of Biancavilla (Catania, Italy) with the aim of explaining the nature of the high As and F contents of the area's rocks. As and F contents in soils and groundwater were also investigated. The metasomatised benmoreite lavas show fluorine and arsenic concentrations up to about 3,000 and 1,000 mg/kg, respectively. Mineralogical analyses show that fluorine occurs mostly in fluoro-edenite and apatite-(CaF) crystals, both abundantly present in the altered rocks, while As is exclusively attributed to the apatite-(CaF) crystals. Specifically, arsenic was observed only at the borders of these apatite crystals. Leaching tests and sequential extraction procedures were carried out to evaluate the potential remobilisation of As and F by the mineral phases and the eventual risks induced by their spreading. The results of the leaching tests suggest that As is almost totally associated with the 'easily reducible' fraction and that it is released by the preferential dissolution of the arsenic enriched rims of apatite-(CaF) crystals. In soils, As concentration is relatively low (about 15 mg/kg, on average), while F ranges from 236 to 683 mg/kg. The underground waters supplying the town of Biancavilla show As and F contents lower than the allowed limits for drinking water, (As:10 mu g/L, F:1-1.5 mg/L). The limited distribution of these rocks and the relatively limited mobilisation by the minerals both contribute to maintain low As and F values, in soils and groundwaters, despite the high values in metasomatised lava samples