Matteo Giordani

This study presents new morphological, mineralogical, and chemical data on fibrous erionite, a carcinogenic zeolite, discovered for the first time in the volcanic rocks of the Vulsini Volcanic District, Italy. The erionite fibers were investigated using OM, TGA, SEM-EDS, XRPD, and EDXRF techniques. They occur as inhalable aggregates composed of extremely thin, tangled crystals with very high aspect ratios, features that may enhance both inhalability and toxicological significance. Mineralogical associations with saponite indicate formation under low-temperature hydrothermal conditions (<150 °C), likely related to late- to post-magmatic fluid circulation through cavities and vesicles in the host volcanic rocks. Chemical analyses identify the zeolite as erionite-K, reflecting the potassic character of associated volcanic lithologies and highlighting the influence of host-rock and fluid chemistry on zeolite formation. Trace-element contents, particularly in As, V, Rb, and Pb, may represent an additional factor influencing fiber toxicity through synergistic effects. The occurrence of carcinogenic fibrous erionite in volcanic lithologies widely exploited for quarrying and industrial applications raises significant environmental and occupational health concerns for zeolitized volcanic terrains in central Italy. These findings highlight the need for detailed fiber characterization and mineralogical investigations to support exposure prevention and environmental risk assessment in future excavation and quarrying activities.

The present study investigates post-emplacement zeolitization processes in two widespread pyroclastic units from Central Italy: the Cimina Ignimbrite and the Sorano Ignimbrite. A total of seventy-five samples from ten outcrops were analyzed using optical and environmental scanning electron microscopy, electron probe microanalysis, X-ray powder diffraction, and inductively coupled plasma optical emission spectrometry. Analytical results allow the mineral distribution, zeolite composition, textural relationships, and geochemical features of the zeolite-bearing rocks to be defined. In the Cimina Ignimbrite, zeolitization affects the glassy portion of the groundmass, where the glass transforms into a medium- to high-temperature mineral assemblage dominated by clinoptilolite-Ca and cristobalite. This transformation is restricted to the innermost parts of the deposit. In contrast, zeolitization in the Sorano Ignimbrite involves the entire glassy fraction of pumice clasts, with extensive alteration of the glass into medium- to low-temperature zeolites such as chabazite-K and phillipsite-K. The results reveal a significant correlation between the chemical composition of the juvenile material and that of the newly formed zeolites in both types of ignimbrites, particularly in the Sorano Ignimbrite. Zeolitization in Central Italy ignimbrites likely occurs in a natural autoclave-like setting, where hot fluids remain trapped in the deposit for a long time.

Recently, high amounts of toxic and radioactive elements have been discovered in epsomite crystals in the abandoned sulphur mine of Perticara, Italy (Giordani et al., 2022). Epsomite represents a neoformed mineral grown in the galleries after the extraction activities of the sulfur mine. In particular, a content of 5.59 ± 0.84 Bq/g of 210Po was detected in the epsomite phase, coupled with other toxic elements such as 228Th, As, Co, Fe, Mn, Ni, Sr, Ti, Zn.The anomalous content of polonium led to new investigations of the area through the study of different matrices present in the galleries: minerals, host-rock, water, air, dust and bitumen, with the aim to define the origin and the distribution of this hazardous element. The samples were investigated combining several analytical techniques: X-ray Powder Diffraction (XRPD), Environmental Scanning Electron Microscopy (ESEM-EDS), Inductively Coupled Plasma-Atomic Emission (ICP-AES), Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), Atomic Absorption Spectrometry (AAS), Gamma Spectrometry, Alpha Spectrometry, Radon Monitor, and Alpha Track Detector (ATD).Water samples showed high Al, Fe, Pb, Mg, and Mn content but not radioactive elements. The bitumen sample showed a higher amount of 210Po and 210Pb (0.12 ± 0.02 Bq/g and 0.11 ± 0.02 Bq/g, respectively), compared to the host-rock and fibrous sericolite samples, but lower than fibrous epsomite crystals (210Po 5.59 ± 0.84 Bq/g; 210Pb 5.93 ± 1.19 Bq/g). A slight anomaly in the 40K and 226Ra content of the host-rock was observed (0.38 ± 0.05 Bq/g and 0.052 ± 0.007 Bq/g respectively), and a high 222Rn concentration (up to 2200 ± 300 Bq/m3) was also detected in the tunnels (Giordani et al., 2024).The confined atmosphere of the mine, with the high 222Rn concentration, is likely the source of the high level of 210Po and 210Pb, in radioactive equilibrium, detected in epsomite. Thus, the 222Rn-rich, anoxic, and hypoxic atmosphere, coupled with the abundance of Mn, Fe, and organic matter in the mine, could play a key role in the 210Po remobilization. This work highlighted that natural epsomite, which is a very common mineral phase in mines, caves, and underground environments, is able to capture 210Po and 210Pb. For this reason, it should be used as a mineral indicator for the presence of radioactive elements in similar environmental conditions, also helping to ensure safe management. These results indicate that in areas with a long history of mining, despite decommissioning, environmental hazards and human health risks may still emerge in terms of radioactivity and potentially toxic elements (PTEs). Giordani, M., Meli, M.A., Roselli, C., Betti, M., Peruzzi, F., Taussi, M., Valentini, L., Fagiolino, I. and Mattioli, M., 2022. Could soluble minerals be hazardous to human health? Evidence from fibrous epsomite. Environmental Research, 206, p.112579.Giordani, M., Taussi, M., Meli, M.A., Roselli, C., Zambelli, G., Fagiolino, I. and Mattioli, M., 2024. High-levels of toxic elements and radioactivity in an abandoned sulphur mine: Insights on the origin and associated environmental concerns. Science of the Total Environment, 906, p.167498.

We report the occurrence of natural calcium silicate hydrates (C-S-H) from the Grolla quarry in the Lessini Mountains of Northern Italy. These minerals are formed by basic and ultrabasic magma interacting with carbonate rocks. The mineral assemblage includes thaumasite, xonotlite, tobermorite, and plombierite, often intergrown with other silicates, as well as minor amounts of carbonates and sulfates. Common zeolites in this area include chabazite, phillipsite/harmotome, natrolite, and thomsonite. Although less abundant, these zeolites are typically associated with calcite, fluoroapophyllite, and barite. The Grolla quarry outcrop allows for the study of the in situ complex crystalline overgrowths and specific crystal chemistry of rare natural mineral phases, such as C-S-H minerals, formed under metasomatic to hydrothermal conditions.

Exposure to mineral fibers represents an occupational and environmental hazard since particulate inhalation leads to several health disorders. However, few data are available on the effect of fibers with high solubility like natural epsomite, a water‐soluble fiber with an inhalable size that allows it to penetrate biological systems, with regard to the respiratory tract. This study evaluated the natural (fibrous epsomite) and synthetic (Epsom salt) magnesium sulfate pathogenicity. Investigations have been performed through morpho‐functional and biochemical analyses, in an in vitro cell model that usually grows as monocytes, but that under appropriate conditions differentiates into macrophages. These latter, known as alveolar macrophages, if referred to lungs, represent the first line of defense against harmful inhaled stimuli. Morphological observations reveal that, if Epsom salt induces osmotic stress on cell culture, natural epsomite fibers lead to cellular alterations including thickening of the nuclear envelope and degenerated mitochondria. Moreover, the insoluble fraction (impurities) internalized by cells induces diffuse damage characterized at the highest dosage and exposure time by secondary necrosis or necrotic cell death features. Biochemical analyses confirm this mineral behavior that involves MAPK pathway activation, resulting in many different cellular responses ranging from proliferation control to cell death. Epsom salt leads to MAPK/ERK activation, a marker predictive of overall survival. Unlike, natural epsomite induces upregulation of MAPK/p38 protein involved in the phosphorylation of downstream targets driving necrotic cell death. These findings demonstrate natural epsomite toxicity on U937 cell culture, making the inhalation of these fibers potentially hazardous for human health.Research Highlights: Natural epsomite and synthetic Epsom salt effects have been evaluated in U937 cell model. Epsom salt induces an osmotic cellular stress. Natural epsomite fibers lead to cellular damage and can be considered potentially dangerous for human health.