Structural and spectroscopic characterization of a suite of fibrous amphiboles with high environmental and health relevance from Biancavilla (Sicily, Italy)

Abstract

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

Thermal inertization of amphibole asbestos modulates Fe topochemistry and surface reactivity

“…Comparison with room temperature data of Pacella et al ( 2010) indicates a slightly different iron content, Fe 2+ /Fe 3+ ratio and a corresponding Fe 2+ /Fe 3+ partition (Table 4) for tremolite. Those differences can be related to the common chemical variability exhibited by amphibole fibres (Andreozzi et al, 2009) and are consistent with the observed small differences between cell parameters and volume (Table 1) (Ballirano et al, 2017). Consistently with calorimetric data, XRPD of tremolite heated at 1200°C indicated that breakdown products consist of two pyroxenes, namely diopside-like and pigeonite-like, minor cristobalite and hematite traces the latter deriving from tremolite breakdown (Table 3).…”

Towards a detailed comprehension of the inertisation processes of amphibole asbestos:in situhigh-temperature behaviour of fibrous tremolite

“…Heating run (1), (2) and (5), carried out on pristine samples, provide slightly different X 0 , a 0 and a 1 parameters of the Berman equation. This fact is caused by the reported small chemical variability typical of the tremolite sample from Maryland (Pacella et al , 2010, 2020), and of amphibole fibres in general (Gianfagna et al , 2007; Andreozzi et al , 2009). The behaviour of the re-heated samples will be discussed below.…”

New morphological, chemical, and structural data of woolly erionite-Na from Durkee, Oregon, U.S.A.

“…This task is inherently very difficult for fibers and especially for zeolites because of the well-known problems related to the small crystal dimensions and their instability under the electron beam that leads to fairly unreliable analytical results. As far as the structural characterization of fibers is concerned, a significant number of papers fully exploiting the capabilities of laboratory parallel-beam transmission X-ray powder diffraction have been recently published Pacella et al 2008;Andreozzi et al 2009;Ballirano and Cametti 2012). This instrumental set up coupled with the preparation of the sample as a capillary mount allows an almost complete removal of preferred orientation and therefore significantly improving the reliability of the structural data even at non-ambient conditions (Ballirano 2011a(Ballirano , 2011b(Ballirano , 2011c.…”