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Multi-analytical approach for an archaeometric study on orichalcum coins
Full text linkOrichalcum is a Cu-Zn based alloy known since the 1st millennium BC. The cementation was the ancient technique used for its production. The PhD project here presented aimed to characterise this alloy and to evaluate its degradation: for this purpose, non-destructive, nano-invasive and destructive techniques were used on a collection of ancient coins issued from the 1st century BC to the end of the 1st century AD. In particular, a multi-analytical approach was used: to investigate the patinas and their corrosive patterns, to study the alloy microstructures and their degradation, to describe the dezincification process and grouping the coins by emission. In addition, quantitative analyses allowed a complete characterization of this ancient alloy. The multi-analytical approach allowed to review the previous theories used for dating samples in orichalcum. This project wanted to contribute to the current knowledge on Roman coinage and to attempt to investigate the mechanisms of corrosive processes affecting ancient alloys
Archaeometric study on orichalcum coins
Full text linkmetalli, puri o in lega, hanno sempre giocato un ruolo fondamentale nella storia dell’uomo: la produzione regolare di oggetti in rame, ferro, bronzo e oricalco in antichità è infatti attestata dai numerosi ritrovamenti archeologici. In particolare, l’oricalco è una lega a base di rame e zinco, simile al moderno ottone, considerata dagli antichi un’invenzione degli dei. L’antica tecnica utilizzata per la produzione dell’oricalco era la cementazione, diffusa sia in Oriente che tra i popoli del bacino mediterraneo. Usato sin dal primo millennio a.C. in Asia Minore, l’oricalco fu introdotto come lega per la monetazione nel secondo secolo a.C. in Anatolia e solo successivamente nella penisola italica. Qui, Giulio Cesare per primo produsse monete in oricalco, come emissione sperimentale. Ottaviano Augusto, nel 23 a.C., promulgò una riforma monetaria in cui introdusse l’emissione di due nominali in oricalco. Successivamente, con la riforma monetaria di Nerone nel 63-64 d.C. furono introdotti altri tre nominali in oricalco.
La tesi di dottorato di seguito presentata ha lo scopo di caratterizzare la lega di oricalco e valutarne il degrado, attraverso uno studio archeometrico di monete antiche emesse tra il primo secolo a.C. e la fine del primo secolo d.C. Allo scopo, sono state impiegate tecniche non distruttive, nano-invasive e distruttive. In particolare, metodologie superficiali (XRF, FTIR-ATR, VIMP) hanno permesso una prima caratterizzazione delle monete in oricalco e degli strati superficiali della patina. Con tecniche di microscopia (SEM-EDS, FIB-FESEM-EDS, HR-FESEM-EDS) è stato possibile studiare le microstrutture tipiche della lega oricalco, il pattern corrosivo delle patine e il loro sviluppo all’interno dei campioni. L’analisi quantitativa (attraverso l’EMPA) dei nuclei non corrosi e delle patine dei campioni ha consentito la caratterizzazione dell’oricalco e la descrizione del processo di dezincificazione. Attraverso l’approccio multianalitico è stato possibile identificare caratteri di autenticità dei campioni, differenziare le monete per emissione e riesaminare le precedenti teorie utilizzate per la datazione di campioni in oricalco.
Per tanto, con questa tesi di dottorato si è voluto contribuire alle attuali conoscenze sulla coniazione romana in oricalco e si è tentato di approfondire i meccanismi dei processi corrosivi a carico delle leghe antiche.Metals, pure or in alloy, have always played a fundamental role in human history. Indeed, the regular roduction in antiquity of objects in copper, iron, bronze and orichalcum is attested by the numerous archaeological findings. In particular, the orichalcum is a copper-zinc based alloy, similar to the modern brass, considered by the ancient populations an invention of the gods. The cementation was the ancient technique used for the production of the orichalcum, common both in the East and in the Mediterranean basin. Used since the first millennium BC in Asia Minor, the orichalcum was introduced as alloy for coinage in Anatolia in the second century BC and only later was adopted in the Italian peninsula. Here, Julius Caesar first produced coins in orichalcum, as an experimental emission. Octavianus Augustus, in the 23 BC, promulgated a monetary reform, introducing two denominations in orichalcum. Subsequently, with the monetary reform of Nero in 63-64 AD three other denominations in orichalcum were introduced.
The PhD thesis presented below aims to characterise the orichalcum alloy and to evaluate its degradation, through an archaeometric study of ancient coins issued between the first century BC and the end of the first century AD. For this purpose, non-destructive, nano-invasive and destructive techniques were used. In particular, surface methodologies (XRF, FTIR-ATR, VIMP) allowed a first characterization of the orichalcum coins and the superficial investigation of the patinas. With microscopy techniques (SEM-EDS, FIBFESEM-EDS, HR-FESEM-EDS) it was possible to study the typical microstructures of the orichalcum alloy, the corrosive pattern of the patinas and their development within the samples. The quantitative analysis (through the EMPA) of non-corroded cores and patinas of the samples allowed the characterization of the ancient orichalcum and the description of the dezincification process. Therefore, using a multi-analytical approach it was possible to define the authenticity of the samples, to grouping the coins by emission and to review the previous theories used for dating samples in orichalcum.
This PhD thesis wanted to contribute to the current knowledge on Roman coinage in orichalcum and to attempt investigating the mechanisms of corrosive processes affecting ancient alloys
Non-invasive combined FT-IR and NMR protocol to assess the cleaning action of a lignin-based hydrogel on stones
No full textLignocellulosic biomass is found on top of agricultural waste and includes cellulose, lignin, and
hemicellulose. Of the three polymers, only lignin is considered inexpensive and 98% is burned to generate
energy (Vásquez-Garay et al., 2021). Lignin is also an important by-product of paper industry. Due to the
growing interest in converting waste into high-value-added products and thanks to the key properties of lignin,
such as biodegradability, biocompatibility, thermal stability, antioxidant and antimicrobial properties, several
procedures have been developed to regenerate lignin into advanced materials, including hydrogels, nanotubes,
films, nanofibers, and nanoparticles (Akhtar et al., 2016). These are suitable for a variety of applications, such
as drug delivery systems for agriculture or medicine, in water remediation applications, and in sensors since
they can serve as absorbents for heavy metal ions, controlled release agent for controlled delivery and water
retention, smart materials for stimuli response, and biosensors and electrodes (Rico-Garcìa et al., 2020). In this
scenario, a novel emerging application of lignin-based hydrogels could be in the cleaning practice of cultural
heritage stones. This work aimed to evaluate the cleaning potential of a PVA-lignin hydrogel to remove metal
ions from stone surfaces using a non-invasive protocol based on the combination of single-sided NMR and
portable FT-IR (Stagno et al., 2021). Different stones were artificially stained with copper corrosion products
and then cleaned using the lignin-based hydrogel. The spin-spin relaxation time (T2) and the IR spectra were
collected on the stone surface before and after the artificial staining, as well as after the application of the
lignin-based gel. Moreover, FT-IR spectroscopy was also used to study the changes in bonds within the PVAlignin
system before and after being used to clean the stone
Study for the production of a new sustainable additive for restauration mortars
No full textThe strong demand for innovative and sustainable materials for the conservation and the restoration of cultural goods represent a fundamental point in current research in the cultural heritage field. In this context, the NYMPHA project propose a new solution for the restoration and conservation of works of art made of different materials, through the use of a mixture of polysaccharides extracted from microalgae cells (Masi et al., 2021). To this aim, a sustainable protocol for the extraction and purification of polysaccharides has been designed using the unicellular microalga Chlamydomonas reinhardtii. The final product has been characterized from a chemical (FT-IR, Raman and quantitative essays) and biological point of view (antioxidant tests and analysis of resistance to biological attack). From the laboratory characterization, it was possible to compare the polysaccharides composition and the total sugar concentration present in the polysaccharide mixture extracted from Chlamydomonas reinhardtii with other commercial polysaccharides widely used in the restoration sector.
Experiments based on polysaccharide extracts applications on several materials were performed to evaluate their efficacy as consolidant. First of all, tests were carried out on organic (wood and paper) and inorganic surfaces (white marble). Then, the polysaccharide extract was added in restoration mortar. The aim was to contribute to the needs of heritage buildings conservation activities by providing an economical, sustainable, and non-toxic additive with a great level of compatibility with ancient materials. Several samples were realized to evaluate the efficacy of NYMPHA product as additive: samples with two different extract concentration, samples with Primal B60 (acrylic resin) as typical restoration additive and sample without additives as reference. Physical properties of the samples were tested before and after the artificial ageing period in climate chamber and UV chamber, to evaluate differences in mechanical resistance, surface wettability, capillary ability, variation in porosity and to estimate the preservation of the aesthetic characteristics, with colorimetry test. Moreover minero-petrographic and chemical analyses, such as optical microscopy, XRPD, SEM-EDS and FT-IR were realized in order to evaluate changes in the mortar texture, as well as the enhancement of the carbonatation process and, consequently, the consolidation property of the product here proposed.
Masi A., Medeghini L., Masi A., Sadori L., Leonelli F., Favero G. & Antonacci A. (2021) - Natural polysaccharides from microalgae for the protection of cultural heritage. SMART eLAB, 16, 24. https://doi.org/10.30441/smartelab.v16i.12
Archaeometric characterization of XIII century "Provisini" coin: a multi-analytical approach
No full textThe evolution of the corrosion process of medieval objects through IR-spectroscopy
No full textThe investigation of the chemical composition and microstructure of archaeological metal artifacts is
essential for understanding degradation processes, with a particular attention to the corrosion, often triggered
by prolonged periods of burial.
This study focuses on the characterisation of the metal structure of a set of agricultural tools remains
dating from the 13th to 14th centuries, unearthed in the site of Cencelle, a medieval settlement near the Tolfa
Mountains (central Italy), founded in the 9th century and abandoned since the 17th century AD (Annoscia,
2016). The main objective is to understand the underlying causes of degradation, assess conservation status,
and unravel the composition of patinas and corrosion products formed during and after burial period (Grevey
et al., 2020).
To achieve these objectives, a comprehensive multi-analytical approach has been adopted, encompassing
techniques such as Optical Microscopy, Electron Microscopy coupled with Energy Dispersive X-ray analysis,
and Infrared spectroscopy. Significantly, infrared spectroscopy plays a crucial role in identifying both organic
and inorganic materials within the samples, as well as to identify the nature of the patinas and the corrosion
products growth on the samples surfaces also after their preparation.
By analysing data acquired through Infrared spectroscopy, it becomes possible to identify compounds
present in corrosion products and determine their implications on the conservation status of metal artifacts.
This methodological framework offers detailed insights into the nature and composition of materials within the
samples, enhancing understanding of degradation mechanisms, and guiding the formulation of conservation
and restoration strategies.
In conclusion, integrating Infrared spectroscopy with complementary analytical methodologies provides a
robust approach for the systematic examination of archaeological metal artifacts and their associated degradation
processes. The outcomes of this investigation provide substantive contributions towards the preservation and
valorisation of medieval cultural heritage.
Annoscia G. M. (2016) - Per una storia agraria di Leopoli-Cencelle: gli attrezzi agricoli (XIII-XV secolo). Scienze
dell’Antichità 22.1, 177-187.
Grevey A. L. et al. (2020) - Microstructure and long-term corrosion of archaeological iron alloy artefacts. Herit. Sci.,
8(57), https://doi.org/10.1186/s40494-020-00398-9
A multi-analytical approach for the characterization of ancient Roman coins in orichalcum
No full textA selected number of Roman orichalcum coins, from private collections, have been studied. Numismatic analysis indicates that (Crawford, 1974; Sutherland, 1984) they are asses, sestertius and dupondium, minted by Julius Caesar, Augustus and Claudius. The aim of this study was to disclose the chemical composition of the orichalcum alloy, the nature of the patina and corrosion products; orichalcum is an ancient copper based alloy with a variable percentage of zinc (Craddock, 1978). With this aim a multi-analytical approach was involved, i.e. X-ray fluorescence (XRF), scanning electron microscope (SEM-EDS), electron micro probe analyser (EMPA). In particular, XRF analysis was performed on different spots of coins’ surfaces to have information about the chemical composition of the external layers. SEM-EDS analysis allowed to investigate alloy’s microtexture (e.g. segregation micro-domains) and to obtain morphological information. In addition, X-ray maps, acquired across section of coins, give information about elemental distribution inside the alloy; whereas EMPA analysis permits a quantitative chemical composition of major, minor and trace elements composing this ancient alloy. All these techniques confirmed that copper and zinc are the main components of the coins. Other metals, i.e. Fe, Pb, Sn, Co, Ni, As, Sn, Sb and Bi, were also found in the alloy. These elements can provide information about sourcing raw materials sites. Si, S, Cl, K and Ca were found on the surfaces, being contaminant from the soil. Quantitative analysis with microprobe permitted to evaluate the different percentage of Cu and Zn in all the samples. The use of invasive technique (EMPA) was necessary to quantify the abundances of each elements composing the original alloy, thus eliminating soil contaminants and alteration product of the layers developed through time on surfaces. These results, could contribute to fill the lack of knowledge about the orichalcum alloy
New insights on medieval Provisini silver coins by a combination of non-destructive and micro-invasive techniques
No full textThe aim of this research was to characterize ten Provisini, one of the most common silver coins in the Middle Age, dating back to the 13th century A.D. These coins are composed by Ag-Cu alloy and were coined in the Roman mint. A non-destructive, micro-destructive and multi-analytical approach was used, aiming to preserve the surfaces of the coins. The results of XRD and micro-Raman spectroscopy allow defining the alloy composition and the mineralogical nature of the alteration products (e.g. cuprite, tenorite, chlorargyrite, stromeyerite). X-ray maps provided information on major elements distribution on the surface. Finally, Electrochemical Impedance Spectroscopy (EIS) and Voltammetry of Immobilized Micro-Particles (VIMP) permitted to reconstruct the possible scheme of the multi-layering of the patina on the coins. Then, the conservation status was monitored
Protection of dinosaur footprints in carbonate deposits: the case of Sezze (Latium, central Italy) ichnosite
No full textMore than 200 dinosaur footprints were found on three stratigraphic surfaces in the abandoned quarry “Cava Petrianni”, about 70 km south of Rome, nearby the town of Sezze (Latium, central Italy). The ichnosite is located in the westernmost sector of the Lepini Mts., with an exposed carbonate succession belonging to the Lepini-Ausoni-Aurunci Unit. Three distinct trampled surfaces were recognised in a 250-m-thick succession referred to the “Laziale-Abruzzese-Campano domain” deposited in a persistent shallow carbonate platform setting from the Late Triassic to the Late Cretaceous. The footprints, preserved on carbonate platform limestones, are exposed to natural environment degradation (especially karst processes), that can irreversibly modify track morphology, resulting in the loss of details in a site of unique paleontological and paleobiogeographic value (Antonelli et al., 2023). The aim of the present project is to find an appropriate solution in the long-term preservation of dinosaur footprints produced in carbonate deposits from the environmental degradation naturally occurring in paleoichnological and geological sites. The final purpose is both enhancing this palaeontological heritage and proposing a possible solution applicable to other ichnosites with similar conditions. Several consolidants have been tested on the trampled surfaces to evaluate the better in terms of application, costs and results. In particular, a mineral consolidant based on the sol-gel technology (SIOX-5 RE50), a nano-sized silicon dioxide fixative/consolidant in colloidal aqueous dispersion (Nano ESTEL) and TEOS with chitosan were applied. In addition, a bioconsolidation process was tested, applying several bacterial strains, taking advantage from the natural bacterial ability to induce carbonate precipitation (Nigro et al., 2022).
Antonelli M., Romano M., De Sario F., Pignatti J., Sacco E. & Petti F.M. (2023) - Inferred oviraptorosaur footprints in the Apenninic Carbonate Platform: New tools for the identification of trackmakers from the Sezze ichnosite (lower-middle Cenomanian; central Italy). Cretaceous Res., 141, 105362. https://doi.org/10.1016/j.cretres.2022.105362.
Nigro L., Mura F., Toti M.P., Cirigliano A. & Rinaldi T. (2022) - Carbonatogenic bacteria on the ‘Motya Charioteer’ sculpture. J. Cult. Herit., 57, 256-264. https://doi.org/10.1016/j.culher.2022.09.009
Roman orichalcum coins: a deep investigation from patina to core
No full textA set of Roman orichalcum coins, issued from 88 B.C. to 96 A.D., has been investigated using a multi-analytical approach.The aim of the study is to explore the corrosion processes of this alloy, with a special attention to the dezincification and decuprification phenomena, from the external layers to the unaltered core of the samples. Indeed, XRF, VIMP methodology and ATR-FTIR were used to obtain information about the elemental composition (qualitative method) of the external layers and to characterize both the patina and the corrosion pattern of the surfaces, allowing also the analysis of samples that could not be sacrificed. SEM-EDS and FIB-FESEM-EDX analysis allowed to investigate the corrosion micro-texture (e.g. segregation micro-domains) in depth and the unaltered metal core of the coins (Doménech-Carbó et al., 2018). In addition, cross-section analyses at high magnification showed cold-working evidences, i.e. deformed grains and strain lines.Quantitative data of major, minor and trace elements were obtained by means of EMP analysis. Moreover, differences in chemical compositions between the unaltered core and the altered layers of the samples were highlighted. All these techniques revealed the presence of other metal, besides Cu and Zn as the typical elements of orichalcum. Indeed, Tin, Fe, Pb and As are present at different concentrations (from 0.01 to 2.30 % wt). Finally, the interpretation of voltammetric data permitted to group coins, that belong to different monetary emissions, and the discrimination of the issues emitted by different monetary authorities (Di Turo et al., 2017).
Di Turo F., Montoya N., Piquero-Cilla J., De Vito C., Coletti F., Favero G. & Doménech-Carbó A. (2017) - Archaeometric analysis of Roman bronze coins from the Magna Mater temple using solid-state voltammetry and electrochemical impedance spectroscopy. Analytica Chimica Acta, 955, 36–47.
Doménech-Carbó M.T., Di Turo F., Montoya N., Catalli F., Doménech-Carbó A. & De Vito C. (2018) - FIB-FESEM and EMPA results on Antoninianus silver coins for manufacturing and corrosion processes. Scientific Reports, 8, 10676
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