Carlo Aurisicchio’s research while affiliated with Institute of Geosciences and Earth Resources, Italian National Research Council and other places

We report here the results of a multi-analytical approach to characterize twelve Roman coins dating from the third century B.C. to fifth century A.D. that were found in the surroundings of Rome and for which the year of minting is determined by numismatic analysis. The coins were studied using SEM-EDS, EMPA, XRD, and FTIR techniques, enabling semi-quantitative and quantitative determinations of the chemical and mineralogical composition of the alloys and corrosion products. SEM-EDS analyses highlighted the occurrence of corrosion products on the surfaces and wide chemical variations due to selective enrichment or depletions of the alloying metals. The EMP analyses showed that three of the twelve coins are made of copper (1), one is a copper–tin alloy (2), five are copper–tin–lead alloys with elements in different proportions (3), two are copper–lead alloys (4), and another one is a subaerata coin (5). In addition, the physical parameters of the coins, i.e., density, weight, and diameters, were measured to have an overall characterization.

Crystals of beryl from miarolitic pockets, hosted in pegmatitic dikes on the Island of Elba, in Italy, were analyzed for the major and minor elements, including the light elements, by EMPA and SIMS techniques. Back-scattered electron (BSE) images and X-ray maps were used to define the complex textures of these crystals and to highlight the pattern of element distribution in each sample. The majority of the analyzed crystals exhibit a complex pattern of zoning caused by changes in the chemical composition, which follow the main mechanisms of substitution defined for the crystal chemistry of beryl. The following main features are illustrated: (1) the occurrence of crystals with octahedral-site or tetrahedral-site substitutions in different domains of the same crystal, (2) the occurrence of crystals with exclusively tetrahedral or exclusively octahedral substitutions, and (3) the occurrence of crystals or crystal domains having a limited extent of octahedral-site and tetrahedral-site substitutions. However, the analytical data confirm the presence of a gap between the two series, having octahedral-site or tetrahedral-site substitutions. The observed enrichment in Cs and Li is strictly related to the geochemical and petrological features of the LCT host pegmatites. The presence of Ca in some beryl crystals in pegmatites emplaced in carbonate rocks suggests an interaction of the late hydrothermal fluids with country rocks. An enrichment in Fe could also be ascribed to the circulation of fluids having such a contaminant element attributed to the contribution of country rocks or the destabilization of early-crystallized Fe-rich minerals. Keywords: beryl, EMPA and SIMS data, BSE images, X-ray maps, crystal chemistry, substitution mechanisms, miarolitic pockets, LCT pegmatite, Island of Elba, Italy.

The present study refers to the characterization of an emerald and gold necklace, dating from the first century AD, found in Oplontis (Torre Annunziata, Naples, Italy), using non-destructive methodologies such as EPMA and microFTIR. Reference samples, from mines known to be active in the Roman Imperial period, were collected and analyzed using the same techniques. Experimental data were also statistically treated in order to classify the emeralds' mines. The comparison of archaeological and reference data allowed to hypothesize, with high probability, an Egyptian origin for the Oplontis emeralds – even if the Habachtal mine cannot be definitively excluded.

The Anjanabonoina rare-element-enriched granitic pegmatite dikes, located about 40 km southwest of Betafo, in central Madagascar. are emplaced in a complex environment characterized by paragneiss, marble and orthogneiss of the Neoproterozoic Itremo Group. of medium metamorphic grade. The subhorizontal bodies of pegmatite are strongly zoned and, in the mineralized area called Sarodivotra, they show a rich paragenetic assemblage in which Ti-Nb-Ta-bearing minerals occur. We recognize two generations of pyrochlore-group and columbite-group minerals. They have a high Nb:Ta ratio, with predominance of Nb- and Ti-dominant phases, and a rare late development of Ta-bearing minerals in fractures. Crystals of the first generation, Nb-dominant (1.20-1.23 apfu), are pyrochlore, whereas those of the second generation, mainly Ti-dominant, are U-rich betafite (0.29-0.57 apfu U) and locally pyrochlore. The primary minerals are typical of an NYF-type pegmatite, and contrast with the LCT-type mineralogy (which includes abundant elbaite-liddicoatite, a pink variety of beryl, spodumene, and hambergite) typical of much of the Anjanabonoina dike. Large crystals of pyrochlore of the first generation are affected by a primary alteration, at high temperature, due to circulation of hydrothermal fluids, represented by the substitution (CaO)-Ca-A-O-Y-->(A)square(Y)square at the core, and by a secondary alteration (at low temperature) along fractures and at the rim, during which the vacancies increased in the A and Y sites. Crystals of the second generation are even more intensely altered. The columbite-group mineral. also formed in two generations and by exsolution in pyrochlore, is fersmite. Rarely, fersmite replaces pyrochlore in the second-generation crystals. We use pyrochlore-and columbite-group minerals to monitor magmatic evolution and postmagmatic events related to circulation of the hydrothermal fluids and weathering-type reactions.

During the archaeological survey in view of an urbanistic project in the ancient Tenuta Boccone D’Aste (north-eastern area of Rome), an important necropolis dating back to the Roman empire (second century A.D.) came to light. A complete archaeological investigation revealed the existence of 80 tombs. Among them, tomb 75 was particularly interesting, containing the skeleton of a young woman inhumed and several grave goods as a cosmetic trousseau, including a silver lock and a silver object consisting of a metallic cylindrical inner part threading beads, probably a distaff. It appeared to be partially covered with a red residue. Chemical–physical analyses carried out on all the materials constituting the distaff, with particular attention to the red layer, revealed the presence of an iron support threading amber beads. The red pigment, most likely used to decorate a wooden box, resulted to be cinnabar commonly used in the Imperial Age as a colouring material.

The Li, B and H contents of foitite were investigated for the first time by means of secondary ion mass spectrometry (SIMS). The studied foitite occurs in the pockets of Elba pegmatites, not only as previously described, acicular and fibrous crystals, but also as black-violet, fibrous-to-prismatic overgrowth at the terminations of elbaitic, polychrome tourmalines. A variety of compositions, belonging to the foitite-schorl solid solution, were recognised. Foititic compositions observed as overgrowths of polychrome crystals are associated with the crystallisation of zeolites at the beginning of a zeolite hydrothermal stage. Morphologically similar overgrowths, but richer of schorlitic component. are associated with later hydrothermal circulation along late-stage fractures that crosscut the pegmatites and the host monzogranite.

The research of reference materials is of primary importance for the correct data processing with microbeam methods, in the case of silicates containing light and volatile elements, i.e., H, Li; Be, B and F, the problems of finding reference samples are enhanced by analytical difficulties and inhomogeneities in the chemical composition of natural phases. In this study, a large, pink-red coloured fragment of a tourmaline crystal from the Lacamisinten gem deposit (Fianarantsoa district, Central Madagascar) was investigated by different analytical techniques, e.g., electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS), crystal-Structure REFinement (SREF), atomic absorption (AA), thermogravimetric analysis (TGA) and gas-chromatography (GC) in order to assess its composition, structure and homogeneity. The EMPA study, carried out on three thin sections and a number of fragments, indicates an homogeneous composition in the liddicoatite-elbaite solid solution, with a high Mn content. The SIMS analyses on Li and H give results comparable with those from AA, and GC/TGA, respectively. B data, obtained by the ion microprobe, agree within 1.2-% rel. with those calculated by stoichiometry. The SREF data are in agreement with chemical analysis and show that this sample is homogeneous also by a structural point of view. Depending on these results it is probable that this sample (or a part of it) could be a good reference material for tourmalines of the liddicoatile-(Mn bearing) elbaite solid solution. Further studies, also in terms of B-11/B-10 isotopic ratios, are in progress to investigate more extensively any local variation in the chemical composition of the sample, and in order to identify the most homogeneous portion of the crystal that could be used as a reliable reference material for elemental as well as isotopic micro-analytical work.