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The first part of this study reports on the wide campaign for the extension of the database of both trace and minor elements concentration in diopside by means of μ-PIXE measurements and of luminescence spectra in diopside and wollastonite by means of μ-IL measurements. Diopside and wollastonite are actually two of the most common lapis lazuli-forming minerals. For this former part of the study, we analysed rocks of known provenance at the microbeam line of the LNL laboratories in Legnaro (PD) of the Istituto Nazionale di Fisica Nucleare (INFN). The latter part of the paper is dedicated to the non-invasive Ion Beam Analyses (IBA) characterisation of six pieces of the “Collezione Medicea”. The collection is exhibited at the Museum of Natural History (University of Firenze) and belonged to the Medici family. It includes artworks made of lapis lazuli manufactured in the 16th and 17th centuries but there is not precise information about the provenance of the used raw material. Results on the artworks show, as expected, that the Chilean provenance of the material used for the analysed artworks has to be excluded. Lapis lazuli used for five of the analysed artworks can be ascribed to the Afghan quarry district, while one object cannot be attributed only on the base of diopside and wollastonite analysis.

Lapis lazuli has been used for glyptics and carving since the fifth millennium BC to produce jewels, amulets, seals, inlays, etc; the identification of the origin of the stone used for carving artworks may be valuable for reconstructing old trade routes. Since ancient lapis lazuli art objects are precious, only non-destructive techniques can be used to identify their provenance, and ion beam analysis (IBA) techniques allow us to characterise this stone in a fully non-invasive way. In addition, by using an ion microprobe, we have been able to focus the analysis on single crystals, as their typical dimensions may range from a few microns to hundreds of microns. Provenance markers, identified in previous IBA studies and already presented elsewhere, were based on the presence/absence of mineral phases, on the presence/quantity of trace elements inside a phase and on characteristic features of the luminescence spectra. In this work, a systematic study on pyrite crystals, a common accessory mineral in lapis lazuli, was carried out, following a multi-technique approach: optical microscopy and SEM-EDX to select crystals for successive trace element micro-PIXE measurements at two Italian facilities, the INFN Laboratori Nazionali di Legnaro and the INFN LABEC laboratory in Firenze. The results of this work allowed us to obtain new markers for lapis lazuli provenance identification.

In this paper we report about the micro-PIXE characterisation of lapis lazuli, for a provenance study of this semi-precious stone, used for glyptic as early as 7000 years ago. The final aim is to find markers permitting to identify the origin of the raw material coming from three quarries in regions of historical importance: Afghanistan, Pamir Mountains and Siberia. This may help to reconstruct trade routes, especially for ancient objects for which written testimonies are scanty or absent at all. Due to the heterogeneity of lapis lazuli we concentrate our attention on single phases instead of the whole stone; in particular we focused on two of the main phases: lazurite, responsible for the blue colour, and diopside, the most frequent accessory mineral. This study was preceded and completed by means of microanalysis with Scanning Electron Microscopy (SEM-EDX) and Cold-Cathodoluminescence (cold-CL) analysis. Despite the limited number of analysed samples, results are sufficient to exclude/suggest a few features as provenance markers, partly confirming what has been previously published in literature.

Metals are one of the major classes of environmental contaminants and raise concerns for their adverse effects on ecosystems. Ants are good candidates as bioindicators for metal contamination assessment; previous studies indeed showed that ants are able to selectively accumulate some metals within their tissues. Available works provide only whole-body burdens of these contaminants, with scarce information on the fine-scale localisation in tissues and organs, although this information is important to better understand the behaviour of metals in living organisms and to clarify their effects in ecosystems. At the Florence external scanning microbeam, we are carrying on a Particle Induced X-ray Emission (PIXE) study on a common ant species sampled from sites with different environmental metal availabilities. Measurements were carried out on resin-embedded, self-standing sections for a direct localisation of metal deposits and an easy determination of their content. The combined use of the PIXE and the external scanning microbeam made it possible to map element distributions with good spatial resolution and sensitivity, restricting quantitative analyses to the metal accumulation regions. To determine in which tissues/organs metals concentrated, we compared PIXE maps with histological images on sections contiguous to the analysed slices. Measurements in the external set-up allowed us to avoid sample damaging. Differences in metal concentrations in ants from different sites resulted from quantitative PIXE analyses. Copyright © 2011 John Wiley & Sons, Ltd.

Fluid inclusions are small portions, usually smaller than 100 μm, of fluid trapped within minerals during or after growth. Their characteristics provide therefore fundamental information on nature and evolution of fluids present in the past in different geological environments. At the LABEC laboratory in Firenze, high-salinity fluid inclusions in quartz crystals, coming from the Apuan Alps metamorphic complex, were analysed at the external scanning microbeam. Results, although still preliminary, have already provided us with hints on fluid-rock interaction processes during the metamorphism of the Apuan Alps.

The Western Alps of Northern Italy mostly consist of lithotectonic units which re-crystallised and were metamorphosed at high depth in a subduction zone. During their exhumation to shallow crustal levels, however, the high-pressure (high-P) mineral assemblages were pervasively re-equilibrated under low-pressure (low-P) conditions, making difficult to estimate the metamorphic thermal peak. Rutile [TiO 2 ] is a typical high-P mineral, occurring as relict phase in low-P re-equilibrated metamorphic rocks. Recent studies suggest that, in thermodynamic systems buffered by the occurrence of quartz and zircon in the rock, Zr content in rutile is a temperature-dependent function that can be modelled quantitatively. An application of rutile Zr-geothermometer to continental and oceanic rocks of the Western Alps, pervasively re-equilibrated under low-P conditions, is presented. The selected rutile crystals were analysed by PIXE using a microbeam set-up at the LABEC laboratory of INFN in Florence. The PIXE spectra and maps were processed by Geopixe software package. Micro-PIXE analyses allowed determining the concentration and the distribution of Zr. Results obtained by applying the rutile Zr-geothermometer gave a more precise indication about the temperatures of the metamorphic conditions suffered by Alpine metamorphic rocks with respect to phase relations and conventional geothermometry, showing that determination of Zr concentration by micro-PIXE technique is a useful tool to reconstruct metamorphic events. The continental units, outcropping in separate zones of Western Alps, show two slightly different thermal peaks (T mean = 530 ± 10 °C and T mean = 555 ± 10 °C) for the same metamorphic event. The oceanic units provide T mean estimates of 575 ± 10°C slightly higher than the continental units.

This work will present preliminary results concerning the use of time-resolved ion beam induced luminescence applied to provenance studies of lapis lazuli. Measurements were performed at the pulsed beam facility at LABEC laboratory in Florence. Lapis lazuli is a semi-precious gemstone, used as ornament since the early civilizations that can be found in few places on Earth. The importance of this work lies in understanding the origin of various samples of lapis lazuli, from which it may be possible to gain insight into trade routes from ancient times. The samples studied in this work originated from Chile, Afghanistan, Tajikistan, Myanmar, and Siberia. The stones were irradiated with 3 MeV protons and the resulting luminescence was detected by a photomultiplier tube, whose output was acquired using a sampling digitizer VME module (CAEN/V1720). Wavelength discrimination was performed at 430 nm utilizing a range of beam currents. The results showed that, by changing the beam current intensity, one can study different features of lapis lazuli, and this may aid in distinguishing lapis lazuli from different provenances.

The external microbeam facility at the 3 MV Tandetron accelerator of the LABEC Laboratory of INFN in Florence has been used to determine, by PIXE, major, minor and trace element abundances of minerals and groundmass in the lavas from the active Nyiragongo Volcano (Democratic Republic of Congo), which is well known for its lava lake intra-crateric activity [e.g. 1, 2]. During the last eruption of this volcano (January, 2002), two main flows entered the Goma town producing major devastation, forcing the rapid exodus of about 300,000 people and causing the death of 150 persons [3]. After this eruption, the interest of the scientific community on this volcanic area suddenly increased. In this respect, determination of major and trace element abundances in mineral phases and groundmass of lavas may allow to constrain the evolution of magma within the volcanic system from a quantitative view point, thus helping to better understand the way this volcano works.

We present a multi-analytical and multi-instrumental approach to a petrologic study of garnets from metapelites characterized by different metamorphic grades. The comparison between major, minor and trace element (Y) distribution in garnets crystallized at different temperatures was performed by electron microprobe (EDS and WDS) and the Proton Induced X-ray Emission microprobe (µ-PIXE). Two garnet samples were selected from metapelite rocks at different metamorphic grades from the tectonic unit of Stilo, Calabrian–Peloritanian Arc, Southern Italy. Quantitative spot analysis profiles and compositional X-ray maps of major elements and yttrium are reported. The major element zoning of garnets is mostly characterized by a smoothed and gradual concentric variation of all elements from core to rim. The Y concentration reveals a marked zoning with its distribution decreasing from about 7000 ppm to about 100 ppm from core to rim, respectively. The precise determination of the Y content by µ-PIXE technique allowed us to better define the rock thermal history, by applying the Y geothermometer. In particular, a common starting temperature of about 450 °C was calculated for the beginning of the garnet growth from all over the unit, but different temperatures in the range from 520 °C to 670 °C were estimated for the peak event in garnets from different areas, in agreement with the P–T values given by the main rock mineral assemblages, reflecting a different metamorphic grade.

Quantitative micro-PIXE and electron microprobe analyses, as well as micro-PIXE compositional mapping of trace elements were performed on monazite [(Ce, La, Nd, Th)PO4] inclusions in pyrope megablasts from Dora Maira Massif, Western Italian Alps for petrological and geochronological purposes.

Broad beam ionoluminescence (IL) microscopy is a promising technique for the non-destructive characterisation of rocks and stone objects. Luminescence imaging by means of broad ion beams has been sporadically used by other authors but, to our knowledge, its potential has not yet been fully investigated, neither in geological science nor in other fields. The in-air broad beam IL microscope was developed and installed at the INFN-LABEC external microbeam in Florence. Similar to the cathodoluminescence (CL) microscope, the apparatus exploits a CCD colour camera collecting images (few square millimetres wide, with ∼10-μm spatial resolution) of the luminescence emitted by the sample hit by a defocused megaelectron volt (MeV) proton beam. The main differences with the well-established and widespread CL are the possibility of working in air (no sampling or conductive coatings required) and the possibility of combining the analysis with microbeam analysis, such as, for example, μ-IL and μ-PIXE (particle-induced X-ray emission). To show the potential of the technique, IL images of thin sections of lapis lazuli are compared with those obtained by means of an in-vacuum cold CL. An application to the study of stone artworks is also reported. This technique and apparatus will provide a valuable help for interdisciplinary applications, e.g. in geological sciences and in the cultural heritage field.

Quantitative micro-PIXE and cathodoluminescence spectra obtained for amazonite crystals from Malawi and Brazil granitoids, in order to check the trace elements presumably responsible for their color. These granitoids, used as Natural Stones for inside coverings and furnishings, are precious and rare, and owe their preciousness to the color of the rock-forming aquamarine amazonite. The trace elements investigated by means of micro-PIXE show the occurrence of Fe, Rb, Pb and Ga at concentrations above the minimum detection limit. In particular, the Malawi amazonite has a higher Pb content than the Brazil amazonite, but for Pb content both samples show a nearly flat pattern profile along the whole crystals. The cathodoluminescence spectra in both samples display three main peaks at 284, 558 and 680 nm which may be attributed to the presence of Pb 2+ , Mn 2+ and Fe 3+ , respectively. As no Mn was detected by PIXE we suggest that its occurrence is below the PIXE detection limit. Micro-PIXE analysis and cathodoluminescence spectra of most common and uncolored K-feldspars do not reveal the presence of lead; therefore we support the hypothesis of Pb as the chromophore source.

The economic interest in natural stones provides an interesting input to the study of coloured rock-forming minerals. Generally, the colour of a mineral is attributed either to the presence of intrinsically-coloured constituents or of trace elements substituting major elements in the crystallographic sites, or to physical factors such as crystal lattice defects. We have analysed the blue and blue-green silicate minerals dumortierite and amazonite, coming from Mozambique quartzites, and from Malawi and Brazil granitoids, respectively. This study was performed by a multiple analytical approach including (a) a comparison of different signals (optical light-polarized images, backscattered electron images and X-ray multielemental maps); and (b) a collection of quantitative data obtained by WDS systems for major elements, and by WDS and/or micro-PIXE facility for trace elements. A good correlation between Ti concentration zoning and pleochroism variations was observed in dumortierite. In addition, the blue dumortierite of Mozambique, with its unusual significant amounts of antimony (about 5 wt.% Sb2O3), represents a mineral with an intermediate composition between dumortierite and holtite. In amazonite the aquamarine colour seems to be related to the Pb content on the order of some hundreds of ppm.