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Fluorine-, boron-, and magnesium-rich metamorphosed xenoliths occur in the Campanian Ignimbrite (CI) deposits at Fiano (southern Italy), at about 50 km northeast of the sourced volcanic area. These rocks originated from Mesozoic limestones of the Campanian Apennines, embedded in a fluid flow. The studied Fiano xenoliths consist of ten fluorophlogopite-bearing calc-silicate rocks and five carbonate xenoliths, characterized by combining mineralogical analyses with whole rock and stable isotope data. The micaceous xenoliths are composed of abundant idiomorphic fluorophlogopite, widespread fluorite, F-rich chondrodite, fluoborite, diopside, Fe(Mg)-oxides, calcite, humite, K-bearing fluoro-richterite and grossular. Out of the five mica-free xenoliths, two are calcite marbles, containing very subordinate fluorite and hematite, and three are weakly meamorphism carbonates, composed of calcite only. The crystal structure and chemical composition of fluorophlogopite approach those of the end member. The Fiano xenoliths are enriched in trace elements with respect to the primary limestones. Comparison between the REE patterns of the Fiano xenoliths and those of both CI and Somma-Vesuvius marble and carbonate xenoliths shows that the Fiano pattern on the whole both overlaps that of Somma-Vesuvius marble and carbonate xenoliths, and yet reproduces the trend of CI rocks. δ13C and δ18O values depict the same trend of depletion in the heavy isotopes observed in the Somma-Vesuvius nodules, related tothermometamorphism. Trace element distribution, paragenesis, stable isotope geochemistry and data modelling point to infiltration of steam enriched in F, B, Mg, As into carbonate rocks at temperature of ca. 300-450°C during the emplacement of the CI.

Fluorine-rich metamorphosed xenoliths associated to the distal Campanian Ignimbrite (CI) tephra (Campania region, southern Italy) have long attracted the interest of the mineralogical community (i.e. Scacchi, 1890; Zambonini, 1919; Masi & Turi, 1972; Balassone et al., 2002). These rocks derive from the Mesozoic carbonate lithotypes of the Campanian Apennine, embedded in the pyroclastic flow and presently resting at the bottom of the tuff formations. The sedimentary protoliths suffered from the action of hot, volatile-rich pyroclastic flow, and consequently were affected by thermal metamorphism to various degrees. Their peculiarity is the occurrence of F- and Mg-bearing phases, with an ubiquitous presence of neoformed fluorite. The occurrence at Fiano quarries (the so-called “Tufare”) is the classical locality for these rock xenoliths. Similar rocks were also found in the CI of the Caserta area, and in the Latium region (Colli Albani). This research aims both at a crystal chemical study of fluorophlogopite occurring in the Fiano xenoliths, and at a geochemical and volcanological survey, to constrain the petrogenesis processes related to this rare F-, Mg-rich assemblage and to CI. The analysed samples belong to two lithotypes: mica-bearing clasts and variably metamorphosed carbonate blocks. The former lithotype is represented by abundant fluorite, followed by fluorophogopite, F-rich chondrodite, fluoborite, diopside and (Fe,Mg)-oxides. Minor to trace contents of calcite, humite, tremolite, and grossular also occur. Carbonate rocks can show calcite only, or also trace amounts of fluorite. The Fiano micas composition approaches that of the Vesuvius micas from the 1872 eruption (Balassone et al., 2013). The micas belong to the 1M polytype and have crystal chemical features typical of fluorophlogopites i.e., low c lattice parameter (~ 10.13 Å), (~ 2.060 Å) and (~ 3.135 Å) distances. New data on minor to ultratrace elements amounts found in the studied clasts, together with Carbon and Oxygen isotope data will be reported and interpreted in a petrogenetic and volcanological frame. Balassone G., Franco E., Mattia C.A., Petti C. & Puliti R. 2002. Re-examination of fluosiderite, an unknown mineral from southern Italy: equal to fluorine-rich chondrodite. Eur. J. Min., 14, 151-155. Balassone G., Scordari F., Lacalamita M., Schingaro E., Mormone A., Piochi M., Petti C. & Mondillo N. 2013. Trioctahedral micas in xenolithic ejecta from recent volcanism of the Somma-Vesuvius (Italy): crystal chemistry and genetic inferences. Lithos, 160-161, 84-97. Masi U. & Turi B. 1972. Frazionamento isotopico del carbonio e dell'ossigeno negli inclusi calcarei metamorfosati del "Tufo grigio campano" Auct. di Fiano (Salerno). Per. Min., 41, 291-310. Scacchi A. 1890. La regione vulcanica fluorifera della Campania. Mem. R. Com. Geol. It., I, 1-48. Zambonini F. 1919. Il tufo pipernoide della Campania e i suoi minerali. Mem. Descr. Carta Geol. It., 7, 130 pp.

A suite of Ti-bearing garnets from magmatic, metamorphic and carbonatitic rocks was studied by Electron Probe Microanalysis (EPMA), X-ray Powder Diffraction (XRPD), Single Crystal X-ray Diffraction (SCXRD), Mössbauer spectroscopy and Secondary Ion Mass Spectrometry (SIMS) in order to better characterize their crystal chemistry. The studied garnets show TiO2 varying in the ranges 4.9(1)-17.1(2) wt.% and variable Fe3+/?Fe content. SIMS analyses allowed quantification of light elements yielding H2O in the range 0.091(7)-0.46(4), F in the range 0.004(1)-0.040(4) and Li2O in the range 0.0038(2)-0.014(2) wt%. Mössbauer analysis provided spectra with different complexity, which could be fitted to a number of components variable from one (YFe3+) to four (YFe2+, ZFe2+, YFe3+, ZFe3+). A good correlation was found between the Fe3+/?Fe resulting from the Mössbauer analysis and that derived from the Flank method (Höfer & Brey, 2007). X-ray powder analysis revealed that the studied samples are a mixture of different garnet phases with very close cubic unit cell parameters as recently found by other authors (Antao, 2013). Single crystal X-ray refinements using anisotropic displacement parameters were performed in the Ia-3d space group and converged to R1 in the range 1.63-2.06 % and wR2 in the range 1.44-2.21 %. Unit cell parameters vary between 12.0641(1) and 12.1447(1) Å, reflecting different Ti contents and extent of substitutions at tetrahedral site. The main substitution mechanisms affecting the studied garnets are: YR4+ + ZR3+ ZSi + YR3+ (schorlomite substitution); YR2+ + ZR4+ 2YR3+ (morimotoite substitution); YFe3+ YR3+ (andradite substitution) with ZR4+ = Ti; YR4+ = Ti, Zr; YR3+ = Fe3+, Al3+, Cr3+; ZR3+ = Fe3+, Al3+ and YR2+ = Fe2+, Mg2+, Mn2+. The 2YTi4++ ZFe2+ 2YFe3+ + ZSi4+, the hydrogarnet substitution [(SiO4)4- (O4H4)4-], the F- OH- and the YR4+ + XR+ YR3+ + XCa2+, with YR4+ = Ti, Zr; YR3+ = Fe3+, Al3+, Cr3+; XR+ = Na, Li also occur. The garnet crystal chemistry and implications in terms of nomenclature and classification (Grew et al., 2013) are discussed. Antao S.M. 2013. The mystery of birefringent garnet: is the symmetry lower than cubic?. Powder diffr., 28(4), 281-287. Grew E.S., Locock A.J., Mills S.J., Galuskina I.O., Galuskina E.V. & Hålenius U. 2013. Nomenclature of the Garnet Supergroup. Am. Mineral., 98, 785-811. Höfer H.E. & Brey G.P. 2007. The iron oxidation state of garnet by electron microprobe: Its determination with the flank method combined with major-element analysis. Am. Mineral., 92, 873-885.

The incorporation of OH- in trace but measurable amounts in the structure of nominally anhydrous minerals is to date well documented. OH- occurring in this manner may constitute the dominant reservoir of hydrogen in the Earth's interior and is believed to play an important role in the physical properties of the mantle. It may also affect the evolution of the hydrosphere through its influence on mantle melting and isotopic fractionation [1]. In Ti-garnets, hydrogen may be incorporated via the hydrogarnet substitution, where a SiO4 unit may locally be replaced by a H4O4-tetrahedron. However, more complex mechanisms have also been proposed [2]. In addition, the uptake of fluorine into the structure is more complex than the simple exchange reaction F- OH- [3]. In this study, Secondary Ion Mass Spectrometry (SIMS) has been used to analyse hydrogen -quantified conventionally as H2O (wt%)-, fluorine and lithium in a suite of Ti garnets of different origin and geological provenance. From Electron Probe Micro-Analysis (EPMA) and structure refinements from single crystal X-ray diffraction (SCXRD) data, such garnets were expected to have tetrahedral substitutions and a hydrogarnet component. FTIR preliminary spectra in the OH- stretching region evidenced that, comparatively, the samples were characterized by various degrees of hydration. The results of our SIMS analyses confirmed the presence of significant amount of H2O (0.091 - 0.459 wt%), low concentration of F (0.0089 - 0.048 wt%) as well as of Li2O (0.0024 - 0.0139 wt%). The comparison with data obtained by X-ray site scattering refinement and Mössbauer spectroscopy allowed to ascertain that the combination of VITi4+VIM3+-1 IVFe3+IVSi-1 (schorlomite substitution) and VIM2+VITi4+VIFe3+-2 (morimotoite substitution), with M3+ = Fe3+, Al3+, and M2+ = Fe2+, Mg2+, Mn2+, can explain most of the chemical variation of tetrahedral and octahedral sites. However, the accurate evaluation of H and F by SIMS favoured the assessment of minor substitution mechanisms. A good qualitative agreement between SIMS and FTIR data was found.

The present study describes the first example of utilization of a natural clay mineral as catalyst in a process addressed to chemical valorization of poly-[bisphenol A carbonate] (PC; (1)) wastes. A natural clinochlore was investigated for the first time as the catalyst of the hydrolysis reaction of 1, a potential route to chemical recycling of wastes of this polymeric material. At 473 K, in tetrahydrofuran (THF) as the solvent, the mineral promoted effectively the depolymerization (up to 99%, after 6 h) of 1 by H2O and the selective (~99%) regeneration of the monomer bisphenol A (BPA, (2)). Temperature, catalyst loading, reaction time, H2O/PC weight ratio affected markedly the productivity of the process. The role of the catalyst was also focused: the experimental data showed that the exposed brucite-like sheets of clinochlore are involved in the hydrolysis reaction and take active part in promoting the depolymerization process.

A multi-methodical characterization of a sauconite (Zn-bearing trioctahedral smectite) specimen from the Skorpion ore deposit (Namibia) was performed by combining X‑ray powder diffraction (XRPD), cation exchange capacity (CEC) analysis, differential thermal analysis (DTA), thermo‑ gravimetry (TG), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM‑HRTEM‑AEM). The X‑ray diffraction pattern exhibits the typical features of turbostratic stacking disorder with symmetrical basal 00l reflections and long‑tailed hk bands, as confirmed by TEM observations. Besides sauconite, the sample contains minor amounts of kaolinite, dioctahedral smectite, and quartz. CEC analysis provides a total of Ca (~69%), Mg (~26%), Na (~4%), and K (0.7%) exchangeable cations. Therefore, Zn is located exclusively within the octahedral site of sauconite. TG analysis of the sample yields a total mass loss of about 17%. Three endothermic peaks can be observed in the DTA curve, associated with dehydration and dehydroxylation of the material. An exothermic peak at 820 °C is also present as a consequence of decomposition and recrystallization. The infrared spectrum shows the typical ZnOH stretching signature at 3648 cm, whereas, in the OH/HO stretching region two bands at 3585 and 3440 cm can be attributed to stretching vibrations of the inner hydration sphere of the interlayer cations and to absorbed HO stretching vibration, respectively. Diagnostic bands of kaolinite impurity at ~3698 and 3620 cm are also found, whereas 2:1 dioctahedral layer silicates may contribute to the 3585 and 3620 cm bands. Finally, using the one-layer supercell approach implemented in the BGMN software, a satisfactory XRPD profile fitting model for the Skorpion sauconite was obtained. These findings have implications not only for economic geology/recovery of critical metals but also, more generally, in the field of environmental sciences., The XRPD laboratory at the Dipartimento di Scienze della Terra and Geoambientali, University of Bari “Aldo Moro”, was funded by Potenziamento Strutturale PONa3_00369 “Laboratorio per lo Sviluppo Integrato delle Scienze e delle TEcnologie dei Materiali Avanzati e per dispositivi innovativi (SISTEMA)”. The XRPD facility at the DiSTAR, University “Federico II” Napoli, is acknowledged. The authors acknowledge Annett Steudel and Katja Emmerich for CEC measurement at the Competence Center for Material Moisture, University of Karlshrue, Germany. GB and NM thank Maria Boni, invaluable scientific guide who promoted the study of the economic geology of worldwide nonsulfide ore deposits, and G. Arfè who firstly characterized the Skorpion samples and for continuous help and fruitful discussions. This work was partly supported by DiSTAR fund 2017 (University of Naples Federico II, Italy) granted to G. Balassone, as well as by the research projects PGC2018-094573-B-100 from the Spanish Government and the Research Group RNM-179 of the Junta de Andalucía granted to F. Nieto. Two anonymous referees are thanked for insightful comments that helped to improve the quality of the manuscript.

Europium-doped hydroxyapatite Ca10(PO4)6(OH)2 (3% mol) powders were synthesized by an optimized chemical precipitation method at 25 &deg, C, followed by drying at 120 &deg, C and calcination at 450 &deg, C and 900 &deg, C. The obtained nanosized crystallite samples were investigated by means of a combination of inductively coupled plasma (ICP) spectroscopy, powder X-ray diffraction (PXRD), Fourier Transform Infrared (FTIR), Raman and photoluminescence (PL) spectroscopies. The Rietveld refinement in the hexagonal P63/m space group showed europium ordered at the Ca2 site at high temperature (900 &deg, C), and at the Ca1 site for lower temperatures (120 &deg, C and 450 &deg, C). FTIR and Raman spectra showed slight band shifts and minor modifications of the (PO4) bands with increasing annealing temperature. PL spectra and decay curves revealed significant luminescence emission for the phase obtained at 900 &deg, C and highlighted the migration of Eu from the Ca1 to Ca2 site as a result of increasing calcinating temperature.

Three samples of (Tl,Sb,As)-rich pyrite from the ore deposits of the southern Apuan Alps (Tuscany, Italy) were studied through a multi -technique approach in order to constrain the speciation and incorporation mechanism of thallium in pyrite. High concentrations of TI, Sb, and As were detected in all the studied samples through laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Average Tl contents were 1299 ppm, 1967 ppm, and 2623 ppm in samples from Sennari, Canale della Radice, and Fornovolasco, respectively. The LA-ICP-MS time-resolved down-hole ablation profiles were smooth indicating that TI, Sb, and As are dissolved in the pyrite matrix, or occur in homogeneously distributed nanoparticles (NPs). X-ray absorption spectroscopy (XAS) data revealed that Tl, Sb, and As occurs as Tl+, Sb3+, As3+, and As In all the studied samples, bond distances and coordination numbers for Sb3+ and Asa" are constant, whereas Tl displays a range of coordination numbers (similar to 3 to similar to 6), revealing the occurrence of different local environments. Moreover, no hints of features corresponding to coordination shells higher than the first were observed, suggesting an extremely disordered environment around Tl. Transmission electron microscopy (TEM) investigations revealed the presence of dislocations and As -rich "fluid" inclusions, whereas no Tl-rich NPs were observed. The study suggests that Tl+ could occur in structural defects in pyrite, lacking any long-range order. The 'loose' nature of TI in pyrite favours its ready loss during the metamorphic recrystallization of pyrite and its redistribution within ore bodies and country rocks, with important implications from an economic and environmental point of view.

This study reports the first crystal chemical database resulting from a detailed structural investigation of trioctahedral micas found in xenolithic ejecta produced during the AD 1631, 1872 and 1944 eruptions, three explosive episodes of recent volcanic period of Vesuvius volcano (Southern Italy). Three xenolith types were selected: metamorphic/metasomatic skarns, pyrometamorphic/hydrothermally altered nodules and mafic cumulates. They are related to different magma chemistry and effusive styles: from sub-plinian and most evolved (AD 1631 eruption) to violent strombolian with medium evolution degree (AD 1872 eruption) to vulcanian-effusive, least evolved (AD 1944 eruption) event, respectively. Both xenoliths and micas were investigated employing multiple techniques: the xenoliths were characterized by X-ray fluorescence, inductively-coupled plasma-mass spectrometry, optical microscopy, X-ray powder diffraction, and quantitative energy-dispersive microanalysis; the micas were studied by electron probe microanalysis and single crystal X-ray diffraction, The mica-bearing xenoliths show variable texture and mineralogical assemblage, clearly related to their different origin. Based on the major oxide chemistry, only one xenolithic sample falls in the skarn compositional field from the Somma-Vesuvius literature, some fall close to the skarns and cumulate fields, others plot close to the syenite/foidolite/essexite field. A subgroup of the selected ejecta does not fall or approach any of the compositional fields. Trace and rare earth element patterns show some petrological affinity between studied xenoliths and erupted magmas with typical Eu, Ta and Nb negative anomalies. Strongly depleted patterns were detected for the 1631 metamorphic/metasomatic skarns xenoliths. Three distinct mica groups were distinguished: 1) Mg-, Al-rich, low Ti-bearing, low to moderate F-bearing varieties (1631 xenolith), 2) Al-moderate, F- and Mg-rich, Ti-, Fe-poor varieties (1872 xenolith), and 3) Al-, Ti- and Fe-rich, F-poor phases (1944 xenolith). All the analyzed mica crystals are 1M polytypes with the expected space group C2/m. Micas from xenoliths of the 1631 Vesuvius eruption are phlogopites characterized by a combination of low extent of oxy-type and variable extent OH- --> F- substitutions, as testified by the range of F concentration (from similar to 0.20 to 0.80 apfu). Micas from xenoliths of the 1872 Vesuvius eruption exhibit structural peculiarities typical of fluorophlogopites, i.e. OH- --> F- substitution is predominant. Micas from the xenolith of the 1944 Vesuvius eruption display features typical of oxy-substituted micas. The variability of the crystal chemical features of the studied micas is consistent with the remarkable variation of their host rocks. Micas from 1631 nodules are related to metasomatic, skarn-type environment, deriving from the metamorphosed wall-rocks hosting the magma reservoir. The fluorophlogopites from the 1872 xenoliths testify for strongly dehydrated environmental conditions compared to those of the 1631 and 1944 hosts. Finally, magma storage condition at depth, associated to a decreasing a(H2O) may have promoted major oxy-type substitutions in 1944 biotites.