Roberto Cossio

The term "archaeometry" was first used in 1958 as the title of a special volume published by the Research Laboratory for Archaeology and Art History at Oxford University. Archaeometry is a scientific discipline that employs various techniques primarily for the identification of sites, settlement patterns, archaeological stratigraphy, and the production and analysis of found artefacts.Ancient buildings, artifacts, and finds consist predominantly of natural and artificial resources obtained from geological sources. Geosciences techniques are optimal for obtaining information on the origin and technological properties of archaeological artefacts and materials used in cultural heritage from geological sources.This study conducted a petrographic and geochemical analysis of historical mortars from the Roman Theatre of Aosta and the Medieval Sarriod de la Tour Castel located in the Aosta Valley in North-West Italy. Mineralogical phase-specific distribution of elements in mortar samples was calculated using a semi-automated method of image analysis incorporating multivariate statistical analysis of X-ray spectral images. Based on SEM backscattering, a cluster image analysis was conducted to determine the ratio of aggregate, binder, and porosity. Additionally, simple algebraic operations were utilized to fully quantify the oxides in every EDS spectrum, and to compute the distribution of Hydraulicity Index (HI) within the examined domains.This study provided many answers about supply areas, variation of raw materials over time, network/transport systems, development and production processes. The petrographic analysis has enabled identification of both the binder and aggregate type. Specifically, it has afforded information on the type of raw material used to produce the lime, the ratio of binder to aggregate, the origin of the aggregate (sedimentary or crushed rock) and its composition.These investigations were conducted in close collaboration with archaeologists to reconstruct the exchanges between ancient civilizations and evaluate their technological progress.Ultimately, the progress of geosciences within the field of Cultural Heritage highlights how this type of study is essential for the dissemination and museology of what represents the culture of materials from archaeological, historical and scientific point of view.

The ultramafic body of Monte Avic (Aosta Valley, Western Alps, Italy) consists of antigorite serpentinite and Ti-clinohumite metadunite. They host late metamorphic veins, up to a couple of centimeters thick, compact, and homogeneous, with a “porcelain” appearance. Vein colors range from yellowish to light greenish, light yellowish fading to white, or rare orange. The veins consist of 15-sector PS-15 polygonal serpentine, with chemical composition Mg_2.85 Fe_0.08 Si_2.05 O_7.05 [OH]_3.95. Recognition of this unusual phase is supported by diagnostic satellite reflections in the X-ray powder diffraction pattern (e.g., at d_obs of 2.502, 2.336, 2.151, and 1.966 Å) TEM images (showing 15-sector polygonal fibers, mostly 200 nm in diameter and a few µm in length, forming a randomly oriented felt) and a µ-Raman wavenumber, matching previous data. This different evidence affords the successful distinction of PS-15 and PS-30, alternatively using TEM images, X-ray powder diffraction, or the low- and high-wavenumber µ-Raman spectra. At Monte Avic, the vein emplacement was accompanied by significant fluid pressure, as suggested by deformation and dismembering of the host rock, with PS-15 grown within isotropic stress microenvironments characterized by fluid-filled voids. Random growth of the mass-fiber polygonal serpentine was favored by low-strain conditions. PS-15 veins formed at the end of the long polyphase Alpine orogenic evolution, with hydrous fluids possibly deriving from serpentinite dehydration in the depth.

One of the more obscure areas of Roman Republican early coinage are debased quadrigati, which traditionally are deemed to represent the last stage of this coin type. Starting from a pre-screening, based on low specific gravity samples, we first performed neutron diffraction analyses on a larger sample, which allowed us to single out the more debased series. Subsequently, we focused on those series and applied various additional physical investigations on 18 specimens. The focus of this paper is 17 samples displaying very low silver content. They all belong to a very particular group, refereed as “Apulian” quadrigati in previous literature. They are selected for their numismatic differences and to put in evidence the relevant details of their silver quality, which ranges from “apparently good” to “plain bronze.” In this work, we combine rigorous analytical investigations like X-ray fluorescence (both ordinary and micro-), scanning electron microscope, and neutron diffraction to our accurate numismatic classification of the specimens, leading to a clear correlation between series and debasement. This work aims in particular to gain better insights into these mysterious “silver” emissions, bringing new results that can disclose unknown financial and political facts pertaining to the Second Punic War.

Studies on the provenance of raw material used in the production of lapis lazuli artifacts can be particularly useful also in confirming or discarding the attributions given in past times by museum curators. In this work, a case study on five pieces belonging to the 19^th century “Savoy Collection” of the Regional Museum of Natural Sciences in Turin is presented. The analysis allowed to assess the correctness of a previous Chilean attribution and to assign a provenance for the whole set of samples.

Studies on naturally occurring asbestos (NOA) and on the relevant geo-environmental problems have been traditionally focused on metamorphic rocks (and, more recently, on magmatic rocks). Besides these 'primary' occurrences (i.e., those realted to the in situ growth of NOA minerals), 'secondary', detrital NOA may occurr in sediments, sedimentary rocks and soils derived form the erosion of 'primary' NOA bearing rocks.The occurrence of detrital NOA in sediments and soils is increasingly recognized worldwide. However, a few studies exist that investigate the 'sedimentology of NOA', i.e., the mechanisms underlying the genesis, transport, deposition and post-depositional modifications of detrital NOA particles in the different sedimentary environments. A better understanding of these mechanisms would give us the tools to predict the presence and possible concentration of detrital NOA in sediments and sedimentary rocks.The occurrence and distribution of detrital NOA within the Oligocene-Miocene succession of the southern Tertiary Piemonte Basin (NW Italy), will be investigated as a scientific development in the frame of the CARG project (Geological Mapping at 1:50,000 scale - sheet 195 Novi Ligure). This succession consists of stratigraphic units rich in ophiolite clasts and deposited in a variety of sedimentary environments, from continental to deep marine, thus representing an ideal study case. 

The Monte Fico lizardite crystals have an internal skeletal spongy microstructure, formed by two micrometric domains having different optical reliefs. This intracrystalline microstructure parallels the previously reported intercrystalline arrangement, consisting of lizardite prisms within a chrysotile plus polygonal serpentine matrix. In the high-wavenumber region, the larger and more abundant domains (that represent approximately 87 % of the total field view) produce μ-Raman spectra characterized by two major peaks at 3686 and 3705 cm⁻¹. The smaller, less abundant domains present a wide band confined between these wavenumbers. These features are interpreted as lizardite and chrysotile, respectively. Raman results are confirmed by TEM, which emphasizes the presence of well-recognizable polygonal serpentine too. Tight crystallographic control exists between lizardite and this first serpentine generation. A second serpentine generation occurs perpendicularly to the first one. The lizardite crystals grew up with a skeletal habit, whereas chrysotile fibres and polygonal serpentine filled the voids, growing epitactically on the lizardite crystals, with fast crystal growth in a fluid-rich environment.

The serpentine minerals lizardite, polyhedral serpentine, chrysotile, antigorite and 15‐sector and 30‐sector polygonal serpentine have been studied by micro‐Raman spectroscopy, using selected samples, that had been previously characterized. The appropriate crystal orientations were determined by optical microscopy of petrographic sections. Oriented spectra, obtained using Nd‐YAG green laser radiation (532 nm), were deconvolved, extracting wavenumber and intensity values for the peaks, possibly overlapping and forming complex bands. Relevant Raman anisotropy is common and relevant in serpentine. Depending upon the orientation of the impinging laser, significant wavenumber shifts occur (up to 10 cm⁻¹, mostly in polyhedral serpentine and lizardite). Furthermore, also, important intensity variations (up to 1 order of magnitude) occur in polyhedral serpentine, lizardite, chrysotile and antigorite as well. On the one hand, the possibly characteristic peaks have been identified and discussed. On the other hand, caution is suggested as far as the micro‐Raman characterization of polyphasic, variably oriented serpentine minerals is concerned.

A new SEM‐EDS procedure for ancient ceramic classification, based on the automated acquisition and the semiautomated processing of multi‐elemental X‐ray maps, is described. Based on the detection of each aplastic inclusion, the procedure allows to simultaneously obtain a quantitative evaluation of both the inclusion mineral–chemical composition and the ceramic matrix chemical composition. The two data sets can individually or jointly be subjected to statistical methods. The proposed protocol was applied on a set of 22 samples of black glaze pottery from Adrano (north‐eastern Sicily), Hellenistic age (4th to 2nd centuries B.C.). Two main groups emerged from the application of the procedure, mainly distinguished for their quartz–feldspars versus calcium–aluminosilicate relative abundance as the inclusion mineral–chemical composition is concerned and for their matrix SiO ₂ versus CaO. The classification based on the inclusion mineral–chemical data obtained with the proposed method mirrors the results from the traditional OM observation, but when the two data sets are simultaneously considered, a subtler differentiation is observed with the separation of one of the groups in two subgroups, allowing to refine the partition.